diff --git a/src/mtrie.cpp b/src/mtrie.cpp
index 8a838905..5f057e77 100644
--- a/src/mtrie.cpp
+++ b/src/mtrie.cpp
@@ -31,6 +31,7 @@
 
 #include <new>
 #include <algorithm>
+#include <list>
 
 #include "platform.hpp"
 #if defined ZMQ_HAVE_WINDOWS
@@ -71,319 +72,460 @@ zmq::mtrie_t::~mtrie_t ()
 
 bool zmq::mtrie_t::add (unsigned char *prefix_, size_t size_, pipe_t *pipe_)
 {
-    return add_helper (prefix_, size_, pipe_);
-}
+    class mtrie_t *it = this;
+
+    while (size_) {
+        const unsigned char c = *prefix_;
+
+        if (c < it->min || c >= it->min + it->count) {
+            //  The character is out of range of currently handled
+            //  characters. We have to extend the table.
+            if (!it->count) {
+                it->min = c;
+                it->count = 1;
+                it->next.node = NULL;
+            } else if (it->count == 1) {
+                const unsigned char oldc = it->min;
+                class mtrie_t *oldp = it->next.node;
+                it->count = (it->min < c ? c - it->min : it->min - c) + 1;
+                it->next.table = static_cast<class mtrie_t **> (
+                  malloc (sizeof (class mtrie_t *) * it->count));
+                alloc_assert (it->next.table);
+                for (unsigned short i = 0; i != it->count; ++i)
+                    it->next.table[i] = 0;
+                it->min = std::min (it->min, c);
+                it->next.table[oldc - it->min] = oldp;
+            } else if (it->min < c) {
+                //  The new character is above the current character range.
+                const unsigned short oldcount = it->count;
+                it->count = c - it->min + 1;
+                it->next.table = static_cast<class mtrie_t **> (realloc (
+                  it->next.table, sizeof (class mtrie_t *) * it->count));
+                alloc_assert (it->next.table);
+                for (unsigned short i = oldcount; i != it->count; i++)
+                    it->next.table[i] = NULL;
+            } else {
+                //  The new character is below the current character range.
+                const unsigned short oldcount = it->count;
+                it->count = (it->min + oldcount) - c;
+                it->next.table = static_cast<class mtrie_t **> (realloc (
+                  it->next.table, sizeof (class mtrie_t *) * it->count));
+                alloc_assert (it->next.table);
+                memmove (it->next.table + it->min - c, it->next.table,
+                         oldcount * sizeof (class mtrie_t *));
+                for (unsigned short i = 0; i != it->min - c; i++)
+                    it->next.table[i] = NULL;
+                it->min = c;
+            }
+        }
+
+        //  If next node does not exist, create one.
+        if (it->count == 1) {
+            if (!it->next.node) {
+                it->next.node = new (std::nothrow) class mtrie_t;
+                alloc_assert (it->next.node);
+                ++(it->live_nodes);
+            }
+
+            ++prefix_;
+            --size_;
+            it = it->next.node;
+        } else {
+            if (!it->next.table[c - it->min]) {
+                it->next.table[c - it->min] =
+                  new (std::nothrow) class mtrie_t;
+                alloc_assert (it->next.table[c - it->min]);
+                ++(it->live_nodes);
+            }
+
+            ++prefix_;
+            --size_;
+            it = it->next.table[c - it->min];
+        }
+    }
 
-bool zmq::mtrie_t::add_helper (unsigned char *prefix_, size_t size_,
-    pipe_t *pipe_)
-{
     //  We are at the node corresponding to the prefix. We are done.
-    if (!size_) {
-        bool result = !pipes;
-        if (!pipes) {
-            pipes = new (std::nothrow) pipes_t;
-            alloc_assert (pipes);
-        }
-        pipes->insert (pipe_);
-        return result;
+    const bool result = !it->pipes;
+    if (!it->pipes) {
+        it->pipes = new (std::nothrow) pipes_t;
+        alloc_assert (it->pipes);
     }
+    it->pipes->insert (pipe_);
 
-    unsigned char c = *prefix_;
-    if (c < min || c >= min + count) {
-
-        //  The character is out of range of currently handled
-        //  charcters. We have to extend the table.
-        if (!count) {
-            min = c;
-            count = 1;
-            next.node = NULL;
-        }
-        else
-        if (count == 1) {
-            unsigned char oldc = min;
-            mtrie_t *oldp = next.node;
-            count = (min < c ? c - min : min - c) + 1;
-            next.table = (mtrie_t**)
-                malloc (sizeof (mtrie_t*) * count);
-            alloc_assert (next.table);
-            for (unsigned short i = 0; i != count; ++i)
-                next.table [i] = 0;
-            min = std::min (min, c);
-            next.table [oldc - min] = oldp;
-        }
-        else
-        if (min < c) {
-            //  The new character is above the current character range.
-            unsigned short old_count = count;
-            count = c - min + 1;
-            next.table = (mtrie_t**) realloc (next.table,
-                sizeof (mtrie_t*) * count);
-            alloc_assert (next.table);
-            for (unsigned short i = old_count; i != count; i++)
-                next.table [i] = NULL;
-        }
-        else {
-            //  The new character is below the current character range.
-            unsigned short old_count = count;
-            count = (min + old_count) - c;
-            next.table = (mtrie_t**) realloc (next.table,
-                sizeof (mtrie_t*) * count);
-            alloc_assert (next.table);
-            memmove (next.table + min - c, next.table,
-                old_count * sizeof (mtrie_t*));
-            for (unsigned short i = 0; i != min - c; i++)
-                next.table [i] = NULL;
-            min = c;
-        }
-    }
-
-    //  If next node does not exist, create one.
-    if (count == 1) {
-        if (!next.node) {
-            next.node = new (std::nothrow) mtrie_t;
-            alloc_assert (next.node);
-            ++live_nodes;
-        }
-        return next.node->add_helper (prefix_ + 1, size_ - 1, pipe_);
-    }
-    else {
-        if (!next.table [c - min]) {
-            next.table [c - min] = new (std::nothrow) mtrie_t;
-            alloc_assert (next.table [c - min]);
-            ++live_nodes;
-        }
-        return next.table [c - min]->add_helper (prefix_ + 1, size_ - 1, pipe_);
-    }
+    return result;
 }
 
-
 void zmq::mtrie_t::rm (pipe_t *pipe_,
     void (*func_) (unsigned char *data_, size_t size_, void *arg_),
     void *arg_)
 {
+    //  This used to be implemented as a non-tail recursive travesal of the trie,
+    //  which means remote clients controlled the depth of the recursion and the
+    //  stack size.
+    //  To simulate the non-tail recursion, with post-recursion changes depending on
+    //  the result of the recursive call, a stack is used to re-visit the same node
+    //  and operate on it again after children have been visisted.
+    //  A boolean is used to record whether the node had already been visited and to
+    //  determine if the pre- or post- children visit actions have to be taken.
+    //  In the case of a node with (N > 1) children, the node has to be re-visited
+    //  N times, in the correct order after each child visit.
+    std::list<struct iter> stack;
     unsigned char *buff = NULL;
-    rm_helper (pipe_, &buff, 0, 0, func_, arg_);
+    size_t maxbuffsize = 0;
+    struct iter it = {this, NULL, NULL, 0, 0, 0, false};
+    stack.push_back (it);
+
+    while (!stack.empty ()) {
+        it = stack.back ();
+        stack.pop_back ();
+
+        if (!it.processed_for_removal) {
+            //  Remove the subscription from this node.
+            if (it.node->pipes && it.node->pipes->erase (pipe_)) {
+                if (it.node->pipes->empty ()) {
+                    func_ (buff, it.size, arg_);
+                }
+
+                if (it.node->pipes->empty ()) {
+                    delete it.node->pipes;
+                    it.node->pipes = NULL;
+                }
+            }
+
+            //  Adjust the buffer.
+            if (it.size >= maxbuffsize) {
+                maxbuffsize = it.size + 256;
+                buff =
+                  static_cast<unsigned char *> (realloc (buff, maxbuffsize));
+                alloc_assert (buff);
+            }
+
+            switch (it.node->count) {
+                case 0:
+                    //  If there are no subnodes in the trie, we are done with this node
+                    //  pre-processing.
+                    break;
+                case 1: {
+                    //  If there's one subnode (optimisation).
+
+                    buff[it.size] = it.node->min;
+                    //  Mark this node as pre-processed and push it, so that the next
+                    //  visit after the operation on the child can do the removals.
+                    it.processed_for_removal = true;
+                    stack.push_back (it);
+                    struct iter next = {
+                      it.node->next.node, NULL, NULL, ++it.size, 0, 0, false};
+                    stack.push_back (next);
+                    break;
+                }
+                default: {
+                    //  If there are multiple subnodes.
+                    //  When first visiting this node, initialize the new_min/max parameters
+                    //  which will then be used after each child has been processed, on the
+                    //  post-children iterations.
+                    if (it.current_child == 0) {
+                        //  New min non-null character in the node table after the removal
+                        it.new_min = it.node->min + it.node->count - 1;
+                        //  New max non-null character in the node table after the removal
+                        it.new_max = it.node->min;
+                    }
+
+                    //  Mark this node as pre-processed and push it, so that the next
+                    //  visit after the operation on the child can do the removals.
+                    buff[it.size] = it.node->min + it.current_child;
+                    it.processed_for_removal = true;
+                    stack.push_back (it);
+                    if (it.node->next.table[it.current_child]) {
+                        struct iter next = {
+                          it.node->next.table[it.current_child],
+                          NULL,
+                          NULL,
+                          it.size + 1,
+                          0,
+                          0,
+                          false};
+                        stack.push_back (next);
+                    }
+                }
+            }
+        } else {
+            //  Reset back for the next time, in case this node doesn't get deleted.
+            //  This is done unconditionally, unlike when setting this variable to true.
+            it.processed_for_removal = false;
+
+            switch (it.node->count) {
+                case 0:
+                    //  If there are no subnodes in the trie, we are done with this node
+                    //  post-processing.
+                    break;
+                case 1:
+                    //  If there's one subnode (optimisation).
+
+                    //  Prune the node if it was made redundant by the removal
+                    if (it.node->next.node->is_redundant ()) {
+                        delete it.node->next.node;
+                        it.node->next.node = NULL;
+                        it.node->count = 0;
+                        --it.node->live_nodes;
+                        zmq_assert (it.node->live_nodes == 0);
+                    }
+                    break;
+                default:
+                    //  If there are multiple subnodes.
+                    {
+                        if (it.node->next.table[it.current_child]) {
+                            //  Prune redundant nodes from the mtrie
+                            if (it.node->next.table[it.current_child]
+                                  ->is_redundant ()) {
+                                delete it.node->next.table[it.current_child];
+                                it.node->next.table[it.current_child] = NULL;
+
+                                zmq_assert (it.node->live_nodes > 0);
+                                --it.node->live_nodes;
+                            } else {
+                                //  The node is not redundant, so it's a candidate for being
+                                //  the new min/max node.
+                                //
+                                //  We loop through the node array from left to right, so the
+                                //  first non-null, non-redundant node encountered is the new
+                                //  minimum index. Conversely, the last non-redundant, non-null
+                                //  node encountered is the new maximum index.
+                                if (it.current_child + it.node->min
+                                    < it.new_min)
+                                    it.new_min =
+                                      it.current_child + it.node->min;
+                                if (it.current_child + it.node->min
+                                    > it.new_max)
+                                    it.new_max =
+                                      it.current_child + it.node->min;
+                            }
+                        }
+
+                        //  If there are more children to visit, push again the current
+                        //  node, so that pre-processing can happen on the next child.
+                        //  If we are done, reset the child index so that the ::rm is
+                        //  fully idempotent.
+                        ++it.current_child;
+                        if (it.current_child >= it.node->count)
+                            it.current_child = 0;
+                        else {
+                            stack.push_back (it);
+                            continue;
+                        }
+
+                        //  All children have been visited and removed if needed, and
+                        //  all pre- and post-visit operations have been carried.
+                        //  Resize/free the node table if needed.
+                        zmq_assert (it.node->count > 1);
+
+                        //  Free the node table if it's no longer used.
+                        switch (it.node->live_nodes) {
+                            case 0:
+                                free (it.node->next.table);
+                                it.node->next.table = NULL;
+                                it.node->count = 0;
+                                break;
+                            case 1:
+                                //  Compact the node table if possible
+
+                                //  If there's only one live node in the table we can
+                                //  switch to using the more compact single-node
+                                //  representation
+                                zmq_assert (it.new_min == it.new_max);
+                                zmq_assert (it.new_min >= it.node->min);
+                                zmq_assert (it.new_min
+                                            < it.node->min + it.node->count);
+                                {
+                                    class mtrie_t *node =
+                                      it.node->next
+                                        .table[it.new_min - it.node->min];
+                                    zmq_assert (node);
+                                    free (it.node->next.table);
+                                    it.node->next.node = node;
+                                }
+                                it.node->count = 1;
+                                it.node->min = it.new_min;
+                                break;
+                            default:
+                                if (it.new_min > it.node->min
+                                    || it.new_max < it.node->min
+                                                      + it.node->count - 1) {
+                                    zmq_assert (it.new_max - it.new_min + 1
+                                                > 1);
+
+                                    class mtrie_t **old_table =
+                                      it.node->next.table;
+                                    zmq_assert (it.new_min > it.node->min
+                                                || it.new_max
+                                                     < it.node->min
+                                                         + it.node->count - 1);
+                                    zmq_assert (it.new_min >= it.node->min);
+                                    zmq_assert (it.new_max
+                                                <= it.node->min
+                                                     + it.node->count - 1);
+                                    zmq_assert (it.new_max - it.new_min + 1
+                                                < it.node->count);
+
+                                    it.node->count =
+                                      it.new_max - it.new_min + 1;
+                                    it.node->next.table =
+                                      static_cast<class mtrie_t **> (
+                                        malloc (sizeof (class mtrie_t *)
+                                                * it.node->count));
+                                    alloc_assert (it.node->next.table);
+
+                                    memmove (it.node->next.table,
+                                             old_table
+                                               + (it.new_min - it.node->min),
+                                             sizeof (class mtrie_t *)
+                                               * it.node->count);
+                                    free (old_table);
+
+                                    it.node->min = it.new_min;
+                                }
+                        }
+                    }
+            }
+        }
+    }
+
     free (buff);
 }
 
-void zmq::mtrie_t::rm_helper (pipe_t *pipe_, unsigned char **buff_,
-    size_t buffsize_, size_t maxbuffsize_,
-    void (*func_) (unsigned char *data_, size_t size_, void *arg_),
-    void *arg_)
+bool zmq::mtrie_t::rm (unsigned char *prefix_, size_t size_, zmq::pipe_t *pipe_)
 {
-    //  Remove the subscription from this node.
-    if (pipes && pipes->erase (pipe_) && pipes->empty ()) {
-        func_ (*buff_, buffsize_, arg_);
-        delete pipes;
-        pipes = 0;
-    }
+    //  This used to be implemented as a non-tail recursive travesal of the trie,
+    //  which means remote clients controlled the depth of the recursion and the
+    //  stack size.
+    //  To simulate the non-tail recursion, with post-recursion changes depending on
+    //  the result of the recursive call, a stack is used to re-visit the same node
+    //  and operate on it again after children have been visisted.
+    //  A boolean is used to record whether the node had already been visited and to
+    //  determine if the pre- or post- children visit actions have to be taken.
+    bool ret = false;
+    std::list<struct iter> stack;
+    struct iter it = {this, NULL, prefix_, size_, 0, 0, 0, false};
+    stack.push_back (it);
 
-    //  Adjust the buffer.
-    if (buffsize_ >= maxbuffsize_) {
-        maxbuffsize_ = buffsize_ + 256;
-        *buff_ = (unsigned char*) realloc (*buff_, maxbuffsize_);
-        alloc_assert (*buff_);
-    }
+    while (!stack.empty ()) {
+        it = stack.back ();
+        stack.pop_back ();
 
-    //  If there are no subnodes in the trie, return.
-    if (count == 0)
-        return;
+        if (!it.processed_for_removal) {
+            if (!it.size) {
+                if (!it.node->pipes) {
+                    ret = false;
+                    continue;
+                }
 
-    //  If there's one subnode (optimisation).
-    if (count == 1) {
-        (*buff_) [buffsize_] = min;
-        buffsize_++;
-        next.node->rm_helper (pipe_, buff_, buffsize_, maxbuffsize_,
-            func_, arg_);
+                typename pipes_t::size_type erased =
+                  it.node->pipes->erase (pipe_);
+                if (it.node->pipes->empty ()) {
+                    zmq_assert (erased == 1);
+                    delete it.node->pipes;
+                    it.node->pipes = NULL;
+                    ret = true;
+                    continue;
+                }
 
-        //  Prune the node if it was made redundant by the removal
-        if (next.node->is_redundant ()) {
-            delete next.node;
-            next.node = 0;
-            count = 0;
-            --live_nodes;
-            zmq_assert (live_nodes == 0);
-        }
-        return;
-    }
-
-    //  If there are multiple subnodes.
-    //
-    //  New min non-null character in the node table after the removal
-    unsigned char new_min = min + count - 1;
-    //  New max non-null character in the node table after the removal
-    unsigned char new_max = min;
-    for (unsigned short c = 0; c != count; c++) {
-        (*buff_) [buffsize_] = min + c;
-        if (next.table [c]) {
-            next.table [c]->rm_helper (pipe_, buff_, buffsize_ + 1,
-                maxbuffsize_, func_, arg_);
-
-            //  Prune redundant nodes from the mtrie
-            if (next.table [c]->is_redundant ()) {
-                delete next.table [c];
-                next.table [c] = 0;
-
-                zmq_assert (live_nodes > 0);
-                --live_nodes;
+                ret = (erased == 1);
+                continue;
             }
-            else {
-                //  The node is not redundant, so it's a candidate for being
-                //  the new min/max node.
-                //
-                //  We loop through the node array from left to right, so the
-                //  first non-null, non-redundant node encountered is the new
-                //  minimum index. Conversely, the last non-redundant, non-null
-                //  node encountered is the new maximum index.
-                if (c + min < new_min)
-                    new_min = c + min;
-                if (c + min > new_max)
-                    new_max = c + min;
+
+            it.current_child = *it.prefix;
+            if (!it.node->count || it.current_child < it.node->min
+                || it.current_child >= it.node->min + it.node->count) {
+                ret = false;
+                continue;
             }
-        }
-    }
 
-    zmq_assert (count > 1);
-
-    //  Free the node table if it's no longer used.
-    if (live_nodes == 0) {
-        free (next.table);
-        next.table = NULL;
-        count = 0;
-    }
-    //  Compact the node table if possible
-    else
-    if (live_nodes == 1) {
-        //  If there's only one live node in the table we can
-        //  switch to using the more compact single-node
-        //  representation
-        zmq_assert (new_min == new_max);
-        zmq_assert (new_min >= min && new_min < min + count);
-        mtrie_t *node = next.table [new_min - min];
-        zmq_assert (node);
-        free (next.table);
-        next.node = node;
-        count = 1;
-        min = new_min;
-    }
-    else
-    if (new_min > min || new_max < min + count - 1) {
-        zmq_assert (new_max - new_min + 1 > 1);
-
-        mtrie_t **old_table = next.table;
-        zmq_assert (new_min > min || new_max < min + count - 1);
-        zmq_assert (new_min >= min);
-        zmq_assert (new_max <= min + count - 1);
-        zmq_assert (new_max - new_min + 1 < count);
-
-        count = new_max - new_min + 1;
-        next.table = (mtrie_t**) malloc (sizeof (mtrie_t*) * count);
-        alloc_assert (next.table);
-
-        memmove (next.table, old_table + (new_min - min),
-                 sizeof (mtrie_t*) * count);
-        free (old_table);
-
-        min = new_min;
-    }
-}
-
-bool zmq::mtrie_t::rm (unsigned char *prefix_, size_t size_, pipe_t *pipe_)
-{
-    return rm_helper (prefix_, size_, pipe_);
-}
-
-bool zmq::mtrie_t::rm_helper (unsigned char *prefix_, size_t size_,
-    pipe_t *pipe_)
-{
-    if (!size_) {
-        if (pipes) {
-            pipes_t::size_type erased = pipes->erase (pipe_);
-            zmq_assert (erased == 1);
-            if (pipes->empty ()) {
-                delete pipes;
-                pipes = 0;
+            it.next_node =
+              it.node->count == 1
+                ? it.node->next.node
+                : it.node->next.table[it.current_child - it.node->min];
+            if (!it.next_node) {
+                ret = false;
+                continue;
             }
-        }
-        return !pipes;
-    }
 
-    unsigned char c = *prefix_;
-    if (!count || c < min || c >= min + count)
-        return false;
+            it.processed_for_removal = true;
+            stack.push_back (it);
+            struct iter next = {
+              it.next_node, NULL, it.prefix + 1, it.size - 1, 0, 0, 0, false};
+            stack.push_back (next);
+        } else {
+            it.processed_for_removal = false;
 
-    mtrie_t *next_node =
-        count == 1 ? next.node : next.table [c - min];
+            if (it.next_node->is_redundant ()) {
+                delete it.next_node;
+                it.next_node = NULL;
+                zmq_assert (it.node->count > 0);
 
-    if (!next_node)
-        return false;
+                if (it.node->count == 1) {
+                    it.node->next.node = NULL;
+                    it.node->count = 0;
+                    --it.node->live_nodes;
+                    zmq_assert (it.node->live_nodes == 0);
+                } else {
+                    it.node->next.table[it.current_child - it.node->min] = 0;
+                    zmq_assert (it.node->live_nodes > 1);
+                    --it.node->live_nodes;
 
-    bool ret = next_node->rm_helper (prefix_ + 1, size_ - 1, pipe_);
+                    //  Compact the table if possible
+                    if (it.node->live_nodes == 1) {
+                        //  If there's only one live node in the table we can
+                        //  switch to using the more compact single-node
+                        //  representation
+                        unsigned short i;
+                        for (i = 0; i < it.node->count; ++i)
+                            if (it.node->next.table[i])
+                                break;
 
-    if (next_node->is_redundant ()) {
-        delete next_node;
-        zmq_assert (count > 0);
+                        zmq_assert (i < it.node->count);
+                        it.node->min += i;
+                        it.node->count = 1;
+                        class mtrie_t *oldp = it.node->next.table[i];
+                        free (it.node->next.table);
+                        it.node->next.table = NULL;
+                        it.node->next.node = oldp;
+                    } else if (it.current_child == it.node->min) {
+                        //  We can compact the table "from the left"
+                        unsigned short i;
+                        for (i = 1; i < it.node->count; ++i)
+                            if (it.node->next.table[i])
+                                break;
 
-        if (count == 1) {
-            next.node = 0;
-            count = 0;
-            --live_nodes;
-            zmq_assert (live_nodes == 0);
-        }
-        else {
-            next.table [c - min] = 0;
-            zmq_assert (live_nodes > 1);
-            --live_nodes;
+                        zmq_assert (i < it.node->count);
+                        it.node->min += i;
+                        it.node->count -= i;
+                        class mtrie_t **old_table = it.node->next.table;
+                        it.node->next.table =
+                          static_cast<class mtrie_t **> (malloc (
+                            sizeof (class mtrie_t *) * it.node->count));
+                        alloc_assert (it.node->next.table);
+                        memmove (it.node->next.table, old_table + i,
+                                 sizeof (class mtrie_t *) * it.node->count);
+                        free (old_table);
+                    } else if (it.current_child
+                               == it.node->min + it.node->count - 1) {
+                        //  We can compact the table "from the right"
+                        unsigned short i;
+                        for (i = 1; i < it.node->count; ++i)
+                            if (it.node->next.table[it.node->count - 1 - i])
+                                break;
 
-            //  Compact the table if possible
-            if (live_nodes == 1) {
-                //  If there's only one live node in the table we can
-                //  switch to using the more compact single-node
-                //  representation
-                unsigned short i;
-                for (i = 0; i < count; ++i)
-                    if (next.table [i])
-                        break;
-
-                zmq_assert (i < count);
-                min += i;
-                count = 1;
-                mtrie_t *oldp = next.table [i];
-                free (next.table);
-                next.node = oldp;
-            }
-            else
-            if (c == min) {
-                //  We can compact the table "from the left"
-                unsigned short i;
-                for (i = 1; i < count; ++i)
-                    if (next.table [i])
-                        break;
-
-                zmq_assert (i < count);
-                min += i;
-                count -= i;
-                mtrie_t **old_table = next.table;
-                next.table = (mtrie_t**) malloc (sizeof (mtrie_t*) * count);
-                alloc_assert (next.table);
-                memmove (next.table, old_table + i, sizeof (mtrie_t*) * count);
-                free (old_table);
-            }
-            else
-            if (c == min + count - 1) {
-                //  We can compact the table "from the right"
-                unsigned short i;
-                for (i = 1; i < count; ++i)
-                    if (next.table [count - 1 - i])
-                        break;
-
-                zmq_assert (i < count);
-                count -= i;
-                mtrie_t **old_table = next.table;
-                next.table = (mtrie_t**) malloc (sizeof (mtrie_t*) * count);
-                alloc_assert (next.table);
-                memmove (next.table, old_table, sizeof (mtrie_t*) * count);
-                free (old_table);
+                        zmq_assert (i < it.node->count);
+                        it.node->count -= i;
+                        class mtrie_t **old_table = it.node->next.table;
+                        it.node->next.table =
+                          static_cast<class mtrie_t **> (malloc (
+                            sizeof (class mtrie_t *) * it.node->count));
+                        alloc_assert (it.node->next.table);
+                        memmove (it.node->next.table, old_table,
+                                 sizeof (class mtrie_t *) * it.node->count);
+                        free (old_table);
+                    }
+                }
             }
         }
     }
diff --git a/src/mtrie.hpp b/src/mtrie.hpp
index 6d49380c..9a07d504 100644
--- a/src/mtrie.hpp
+++ b/src/mtrie.hpp
@@ -70,14 +70,6 @@ namespace zmq
 
     private:
 
-        bool add_helper (unsigned char *prefix_, size_t size_,
-            zmq::pipe_t *pipe_);
-        void rm_helper (zmq::pipe_t *pipe_, unsigned char **buff_,
-            size_t buffsize_, size_t maxbuffsize_,
-            void (*func_) (unsigned char *data_, size_t size_, void *arg_),
-            void *arg_);
-        bool rm_helper (unsigned char *prefix_, size_t size_,
-            zmq::pipe_t *pipe_);
         bool is_redundant () const;
 
         typedef std::set <zmq::pipe_t*> pipes_t;
@@ -86,13 +78,25 @@ namespace zmq
         unsigned char min;
         unsigned short count;
         unsigned short live_nodes;
-        union {
+        union _next_t {
             class mtrie_t *node;
             class mtrie_t **table;
         } next;
 
         mtrie_t (const mtrie_t&);
         const mtrie_t &operator = (const mtrie_t&);
+
+        struct iter
+        {
+            class mtrie_t *node;
+            class mtrie_t *next_node;
+            unsigned char *prefix;
+            size_t size;
+            unsigned short current_child;
+            unsigned char new_min;
+            unsigned char new_max;
+            bool processed_for_removal;
+        };
     };
 
 }