diff --git a/CMakeLists.txt b/CMakeLists.txt
index a0893007..61303345 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -14,6 +14,7 @@ option(MI_OSX_ZONE          "Use malloc zone to override standard malloc on macO
 option(MI_LOCAL_DYNAMIC_TLS "Use slightly slower, dlopen-compatible TLS mechanism (Unix)" OFF)
 option(MI_BUILD_TESTS       "Build test executables" ON)
 option(MI_CHECK_FULL        "Use full internal invariant checking in DEBUG mode (deprecated, use MI_DEBUG_FULL instead)" OFF)
+option(MI_PADDING           "Enable padding to detect heap block overflow (only in debug mode)" ON)
 
 include("cmake/mimalloc-config-version.cmake")
 
@@ -99,6 +100,11 @@ if(MI_DEBUG_FULL MATCHES "ON")
   list(APPEND mi_defines MI_DEBUG=3)   # full invariant checking
 endif()
 
+if(MI_PADDING MATCHES "OFF")
+  message(STATUS "Disable padding of heap blocks in debug mode (MI_PADDING=OFF)")
+  list(APPEND mi_defines MI_PADDING=0)
+endif()
+
 if(MI_USE_CXX MATCHES "ON")
   message(STATUS "Use the C++ compiler to compile (MI_USE_CXX=ON)")
   set_source_files_properties(${mi_sources} PROPERTIES LANGUAGE CXX )
diff --git a/include/mimalloc-types.h b/include/mimalloc-types.h
index fe4b71b3..3b16b29c 100644
--- a/include/mimalloc-types.h
+++ b/include/mimalloc-types.h
@@ -57,7 +57,7 @@ terms of the MIT license. A copy of the license can be found in the file
 
 // Encoded free lists allow detection of corrupted free lists
 // and can detect buffer overflows, modify after free, and double `free`s.
-#if (MI_SECURE>=3 || MI_DEBUG>=1 || defined(MI_PADDING))
+#if (MI_SECURE>=3 || MI_DEBUG>=1 || MI_PADDING > 0)
 #define MI_ENCODE_FREELIST  1
 #endif
 
@@ -318,8 +318,8 @@ typedef struct mi_random_cxt_s {
   int      output_available;
 } mi_random_ctx_t;
 
-#define MI_PAGES_DIRECT   (MI_SMALL_WSIZE_MAX + MI_PADDING_WSIZE + 1)
 
+#define MI_PAGES_DIRECT   (MI_SMALL_WSIZE_MAX + MI_PADDING_WSIZE + 1)
 
 // A heap owns a set of pages.
 struct mi_heap_s {
diff --git a/src/alloc.c b/src/alloc.c
index 15c6e12f..76342771 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -51,7 +51,7 @@ extern inline void* _mi_page_malloc(mi_heap_t* heap, mi_page_t* page, size_t siz
     mi_heap_stat_increase(heap, normal[bin], 1);
   }
 #endif
-#if defined(MI_PADDING) && defined(MI_ENCODE_FREELIST)
+#if (MI_PADDING>0) && defined(MI_ENCODE_FREELIST)
   mi_padding_t* const padding = (mi_padding_t*)((uint8_t*)block + mi_page_usable_block_size(page));
   ptrdiff_t delta = ((uint8_t*)padding - (uint8_t*)block - (size - __extra_padding));
   mi_assert_internal(delta >= 0 && mi_page_usable_block_size(page) >= (size - __extra_padding + delta));
@@ -209,7 +209,7 @@ static inline bool mi_check_is_double_free(const mi_page_t* page, const mi_block
 // Check for heap block overflow by setting up padding at the end of the block
 // ---------------------------------------------------------------------------
 
-#if defined(MI_PADDING) && defined(MI_ENCODE_FREELIST)
+#if (MI_PADDING>0) && defined(MI_ENCODE_FREELIST)
 static void mi_check_padding(const mi_page_t* page, const mi_block_t* block);
 
 static const mi_padding_t* mi_page_get_padding(const mi_page_t* page, const mi_block_t* block, size_t* bsize) {
diff --git a/src/init.c b/src/init.c
index 3bcc7094..f5ed3014 100644
--- a/src/init.c
+++ b/src/init.c
@@ -32,9 +32,9 @@ const mi_page_t _mi_page_empty = {
 
 #define MI_PAGE_EMPTY() ((mi_page_t*)&_mi_page_empty)
 
-#if defined(MI_PADDING) && (MI_INTPTR_SIZE >= 8)
-#define MI_SMALL_PAGES_EMPTY  { MI_INIT128(MI_PAGE_EMPTY), MI_PAGE_EMPTY(), MI_PAGE_EMPTY(), MI_PAGE_EMPTY() }
-#elif defined(MI_PADDING)
+#if (MI_PADDING>0) && (MI_INTPTR_SIZE >= 8)
+#define MI_SMALL_PAGES_EMPTY  { MI_INIT128(MI_PAGE_EMPTY), MI_PAGE_EMPTY(), MI_PAGE_EMPTY() }
+#elif (MI_PADDING>0)
 #define MI_SMALL_PAGES_EMPTY  { MI_INIT128(MI_PAGE_EMPTY), MI_PAGE_EMPTY(), MI_PAGE_EMPTY(), MI_PAGE_EMPTY(), MI_PAGE_EMPTY(), MI_PAGE_EMPTY() }
 #else
 #define MI_SMALL_PAGES_EMPTY  { MI_INIT128(MI_PAGE_EMPTY), MI_PAGE_EMPTY() }
diff --git a/src/options.c b/src/options.c
index d0cf46cb..7cf90fa8 100644
--- a/src/options.c
+++ b/src/options.c
@@ -390,9 +390,7 @@ void _mi_error_message(int err, const char* fmt, ...) {
 // lsb=1:  bit 63-19: relative file name char* (to `mi_fname_base`), bit 18-1: line number
 // lsb=0:  bit 63-01: return address
 // -----------------------------------------------------------------------------------------------
-#ifndef NDEBUG
 static const char* mi_debug_fname_base    = "mimalloc_fname_base";
-static const char* mi_debug_fname_invalid = "<mimalloc: invalid source name (due to corruption)>";
 
 #define MI_FNAME_SHIFT  16
 #define MI_LINE_SHIFT   (MI_FNAME_SHIFT + MI_INTPTR_SHIFT)
@@ -459,14 +457,14 @@ void* mi_source_unpack(mi_source_t source, const char** pfname, int* plineno) {
     return ((void*)(source.src >> 1));
   }
 }
-#endif
+
 
 // -----------------------------------------------------------------------------------------------
 // Error message for a specific heap block
 // -----------------------------------------------------------------------------------------------
 
 void _mi_page_block_error_message(int err, const mi_page_t* page, const mi_block_t* block, const char* msg) {
-#if defined(MI_PADDING) && defined(MI_ENCODE_FREELIST)
+#if (MI_PADDING>0) && defined(MI_ENCODE_FREELIST)
   const size_t bsize = mi_page_usable_block_size(page);
   const mi_padding_t* const padding = (mi_padding_t*)((uint8_t*)block + bsize);  
   const size_t size = (padding->delta <= bsize ? bsize - padding->delta : bsize);