diff --git a/src/Makefile.am b/src/Makefile.am
index 445f3c8..8a92f49 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -40,8 +40,13 @@ google/protobuf/compiler/c/c_file.h \
 google/protobuf/compiler/c/c_field.h \
 google/protobuf/compiler/c/c_message.h \
 google/protobuf/compiler/c/c_generator.h \
-google/protobuf/compiler/c/c_bytes_field.h
+google/protobuf/compiler/c/c_bytes_field.h \
+google/protobuf-c/protobuf-c-data-buffer.h \
+google/protobuf-c/gskrbtreemacros.h \
+google/protobuf-c/gsklistmacros.h
 
 protobufcinclude_HEADERS = \
 google/protobuf-c/protobuf-c.h \
-google/protobuf-c/protobuf-c-private.h
+google/protobuf-c/protobuf-c-private.h \
+google/protobuf-c/protobuf-c-dispatch.h \
+google/protobuf-c/protobuf-c-rpc.h
diff --git a/src/google/protobuf-c/protobuf-c-dispatch.c b/src/google/protobuf-c/protobuf-c-dispatch.c
index d057b77..2eeea64 100644
--- a/src/google/protobuf-c/protobuf-c-dispatch.c
+++ b/src/google/protobuf-c/protobuf-c-dispatch.c
@@ -239,8 +239,8 @@ allocate_change_index (RealDispatch *d)
     {
       ProtobufCAllocator *allocator = d->allocator;
       unsigned new_size = d->changes_alloced * 2;
-      ProtobufC_FDNotify *n = ALLOC (new_size * sizeof (ProtobufC_FDNotify));
-      memcpy (n, d->base.changes, d->changes_alloced * sizeof (ProtobufC_FDNotify));
+      ProtobufC_FDNotifyChange *n = ALLOC (new_size * sizeof (ProtobufC_FDNotifyChange));
+      memcpy (n, d->base.changes, d->changes_alloced * sizeof (ProtobufC_FDNotifyChange));
       FREE (d->base.changes);
       d->base.changes = n;
       d->changes_alloced = new_size;
@@ -299,6 +299,7 @@ protobuf_c_dispatch_watch_fd (ProtobufCDispatch *dispatch,
   RealDispatch *d = (RealDispatch *) dispatch;
   unsigned f = fd;              /* avoid tiring compiler warnings: "comparison of signed versus unsigned" */
   unsigned nd_ind, change_ind;
+  unsigned old_events;
 #if DEBUG_DISPATCH
   fprintf (stderr, "dispatch: watch_fd: %d, %s%s\n",
            fd,
@@ -314,9 +315,11 @@ protobuf_c_dispatch_watch_fd (ProtobufCDispatch *dispatch,
     {
       if (callback != NULL)
         nd_ind = d->fd_map[f].notify_desired_index = allocate_notifies_desired_index (d);
+      old_events = 0;
     }
   else
     {
+      old_events = dispatch->notifies_desired[d->fd_map[f].notify_desired_index].events;
       if (callback == NULL)
         deallocate_notify_desired_index (d, f);
       else
@@ -325,16 +328,24 @@ protobuf_c_dispatch_watch_fd (ProtobufCDispatch *dispatch,
   if (callback == NULL)
     {
       if (d->fd_map[f].change_index == -1)
-        d->fd_map[f].change_index = allocate_change_index (d);
-      change_ind = d->fd_map[f].change_index;
+        {
+          change_ind = d->fd_map[f].change_index = allocate_change_index (d);
+          dispatch->changes[change_ind].old_events = old_events;
+        }
+      else
+        change_ind = d->fd_map[f].change_index;
       d->base.changes[change_ind].fd = f;
       d->base.changes[change_ind].events = 0;
       return;
     }
   assert (callback != NULL && events != 0);
   if (d->fd_map[f].change_index == -1)
-    d->fd_map[f].change_index = allocate_change_index (d);
-  change_ind = d->fd_map[f].change_index;
+    {
+      change_ind = d->fd_map[f].change_index = allocate_change_index (d);
+      dispatch->changes[change_ind].old_events = old_events;
+    }
+  else
+    change_ind = d->fd_map[f].change_index;
 
   d->base.changes[change_ind].fd = fd;
   d->base.changes[change_ind].events = events;
@@ -407,6 +418,11 @@ protobuf_c_dispatch_dispatch (ProtobufCDispatch *dispatch,
         }
     }
 
+  /* clear changes */
+  for (i = 0; i < dispatch->n_changes; i++)
+    d->fd_map[dispatch->changes[i].fd].change_index = -1;
+  dispatch->n_changes = 0;
+
   /* handle idle functions */
   while (d->first_idle != NULL)
     {
@@ -704,8 +720,8 @@ void protobuf_c_dispatch_destroy_default (void)
 {
   if (def)
     {
-      ProtobufCDispatch *kill = def;
+      ProtobufCDispatch *to_kill = def;
       def = NULL;
-      protobuf_c_dispatch_free (kill);
+      protobuf_c_dispatch_free (to_kill);
     }
 }
diff --git a/src/google/protobuf-c/protobuf-c.c b/src/google/protobuf-c/protobuf-c.c
index 1da81f4..3187f42 100644
--- a/src/google/protobuf-c/protobuf-c.c
+++ b/src/google/protobuf-c/protobuf-c.c
@@ -247,7 +247,8 @@ required_field_get_packed_size (const ProtobufCFieldDescriptor *field,
       return rv + uint32_size (*(const uint32_t *) member);
     case PROTOBUF_C_TYPE_STRING:
       {
-        size_t len = strlen (*(char * const *) member);
+        const char *str = *(char * const *) member;
+        size_t len = str ? strlen (str) : 0;
         return rv + uint32_size (len) + len;
       }
     case PROTOBUF_C_TYPE_BYTES:
@@ -258,7 +259,8 @@ required_field_get_packed_size (const ProtobufCFieldDescriptor *field,
     //case PROTOBUF_C_TYPE_GROUP:
     case PROTOBUF_C_TYPE_MESSAGE:
       {
-        size_t subrv = protobuf_c_message_get_packed_size (*(ProtobufCMessage * const *) member);
+        const ProtobufCMessage *msg = * (ProtobufCMessage * const *) member;
+        size_t subrv = msg ? protobuf_c_message_get_packed_size (msg) : 0;
         return rv + uint32_size (subrv) + subrv;
       }
     }
@@ -501,10 +503,18 @@ static inline size_t boolean_pack (protobuf_c_boolean value, uint8_t *out)
 }
 static inline size_t string_pack (const char * str, uint8_t *out)
 {
-  size_t len = strlen (str);
-  size_t rv = uint32_pack (len, out);
-  memcpy (out + rv, str, len);
-  return rv + len;
+  if (str == NULL)
+    {
+      out[0] = 0;
+      return 1;
+    }
+  else
+    {
+      size_t len = strlen (str);
+      size_t rv = uint32_pack (len, out);
+      memcpy (out + rv, str, len);
+      return rv + len;
+    }
 }
 static inline size_t binary_data_pack (const ProtobufCBinaryData *bd, uint8_t *out)
 {
@@ -517,11 +527,19 @@ static inline size_t binary_data_pack (const ProtobufCBinaryData *bd, uint8_t *o
 static inline size_t
 prefixed_message_pack (const ProtobufCMessage *message, uint8_t *out)
 {
-  size_t rv = protobuf_c_message_pack (message, out + 1);
-  uint32_t rv_packed_size = uint32_size (rv);
-  if (rv_packed_size != 1)
-    memmove (out + rv_packed_size, out + 1, rv);
-  return uint32_pack (rv, out) + rv;
+  if (message == NULL)
+    {
+      out[0] = 0;
+      return 1;
+    }
+  else
+    {
+      size_t rv = protobuf_c_message_pack (message, out + 1);
+      uint32_t rv_packed_size = uint32_size (rv);
+      if (rv_packed_size != 1)
+        memmove (out + rv_packed_size, out + 1, rv);
+      return uint32_pack (rv, out) + rv;
+    }
 }
 
 /* wire-type will be added in required_field_pack() */
@@ -757,11 +775,12 @@ required_field_pack_to_buffer (const ProtobufCFieldDescriptor *field,
       break;
     case PROTOBUF_C_TYPE_STRING:
       {
-        size_t sublen = strlen (*(char * const *) member);
+        const char *str = *(char * const *) member;
+        size_t sublen = str ? strlen (str) : 0;
         scratch[0] |= PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED;
         rv += uint32_pack (sublen, scratch + rv);
         buffer->append (buffer, rv, scratch);
-        buffer->append (buffer, sublen, *(uint8_t * const *)member);
+        buffer->append (buffer, sublen, (const uint8_t *) str);
         rv += sublen;
         break;
       }
@@ -784,9 +803,12 @@ required_field_pack_to_buffer (const ProtobufCFieldDescriptor *field,
         size_t sublen;
         ProtobufCBufferSimple simple_buffer
           = PROTOBUF_C_BUFFER_SIMPLE_INIT (simple_buffer_scratch);
+        const ProtobufCMessage *msg = *(ProtobufCMessage * const *) member;
         scratch[0] |= PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED;
-        sublen = protobuf_c_message_pack_to_buffer (*(ProtobufCMessage * const *) member,
-                                           &simple_buffer.base);
+        if (msg == NULL)
+          sublen = 0;
+        else
+          sublen = protobuf_c_message_pack_to_buffer (msg, &simple_buffer.base);
         rv += uint32_pack (sublen, scratch + rv);
         buffer->append (buffer, rv, scratch);
         buffer->append (buffer, sublen, simple_buffer.data);