diff --git a/source/m3_core.c b/source/m3_core.c
index 75a846cc..b2e4db71 100644
--- a/source/m3_core.c
+++ b/source/m3_core.c
@@ -105,28 +105,34 @@ void *  m3_Realloc  (void * i_ptr, size_t i_newSize, size_t i_oldSize)
 
 #else
 
+static void*
+_c_realloc(void* ptr, size_t old, size_t new)
+{
+    return realloc(ptr, new);
+}
+
 M3AllocationFunctionStruct  m3_alloc_funcs = {
     calloc,
     free,
-    realloc
+    _c_realloc
 };
 
 M3AllocationFunctionStruct  m3_alloc_transient_funcs = {
     calloc,
     free,
-    realloc
+    _c_realloc
 };
 
 M3AllocationFunctionStruct  m3_alloc_memory_funcs = {
     calloc,
     free,
-    realloc
+    _c_realloc
 };
 
 M3Result m3_SetAllocators  (
     void*   (*calloc_fn)    (size_t, size_t),
     void    (*free_fn)      (void*),
-    void*   (*realloc_fn)   (void*, size_t)
+    void*   (*realloc_fn)   (void*, size_t, size_t)
     )
 {
     if ( (calloc_fn == NULL) || (free_fn == NULL) || (realloc_fn == NULL) ) {
@@ -144,7 +150,7 @@ M3Result m3_SetAllocators  (
 M3Result m3_SetTransientAllocators  (
     void*   (*calloc_fn)    (size_t, size_t),
     void    (*free_fn)      (void*),
-    void*   (*realloc_fn)   (void*, size_t)
+    void*   (*realloc_fn)   (void*, size_t, size_t)
     )
 {
     if ( (calloc_fn == NULL) || (free_fn == NULL) || (realloc_fn == NULL) ) {
@@ -159,7 +165,7 @@ M3Result m3_SetTransientAllocators  (
 M3Result m3_SetMemoryAllocators  (
     void*   (*calloc_fn)    (size_t, size_t),
     void    (*free_fn)      (void*),
-    void*   (*realloc_fn)   (void*, size_t)
+    void*   (*realloc_fn)   (void*, size_t, size_t)
     )
 {
     if ( (calloc_fn == NULL) || (free_fn == NULL) || (realloc_fn == NULL) ) {
@@ -189,8 +195,8 @@ void  m3_FreeImpl  (void * io_ptr)
 void *  m3_Realloc  (void * i_ptr, size_t i_newSize, size_t i_oldSize)
 {
     if (UNLIKELY(i_newSize == i_oldSize)) return i_ptr;
-
-    void * newPtr = m3_alloc_funcs.realloc_fn (i_ptr, i_newSize);
+    //  NB: different order of new/old
+    void * newPtr = m3_alloc_funcs.realloc_fn (i_ptr, i_oldSize, i_newSize);
 
     if (LIKELY(newPtr))
     {
@@ -220,8 +226,8 @@ void  m3_FreeTransientImpl  (void * io_ptr)
 void *  m3_ReallocTransient  (void * i_ptr, size_t i_newSize, size_t i_oldSize)
 {
     if (UNLIKELY(i_newSize == i_oldSize)) return i_ptr;
-
-    void * newPtr = m3_alloc_transient_funcs.realloc_fn (i_ptr, i_newSize);
+    //  NB: different order of new/old
+    void * newPtr = m3_alloc_transient_funcs.realloc_fn (i_ptr, i_oldSize, i_newSize);
 
     if (LIKELY(newPtr))
     {
@@ -247,8 +253,8 @@ void  m3_FreeMemoryImpl  (void * io_ptr)
 void *  m3_ReallocMemory  (void * i_ptr, size_t i_newSize, size_t i_oldSize)
 {
     if (UNLIKELY(i_newSize == i_oldSize)) return i_ptr;
-
-    void * newPtr = m3_alloc_memory_funcs.realloc_fn (i_ptr, i_newSize);
+    //  NB: different order of new/old
+    void * newPtr = m3_alloc_memory_funcs.realloc_fn (i_ptr, i_oldSize, i_newSize);
 
     if (LIKELY(newPtr))
     {
diff --git a/source/m3_core.h b/source/m3_core.h
index fc65b65e..dce25913 100644
--- a/source/m3_core.h
+++ b/source/m3_core.h
@@ -158,7 +158,7 @@ typedef struct M3AllocationFunctionStruct
 {
     void* (* calloc_fn)(size_t, size_t);
     void (* free_fn)(void*);
-    void* (* realloc_fn)(void*, size_t);
+    void* (* realloc_fn)(void*, size_t, size_t);
 }
 M3AllocationFunctionStruct;
 
diff --git a/source/wasm3.h b/source/wasm3.h
index a4b64ceb..f2ae7c58 100644
--- a/source/wasm3.h
+++ b/source/wasm3.h
@@ -225,15 +225,15 @@ d_m3ErrorConst  (SuspensionError,               "error during suspension")
 
     M3Result            m3_SetAllocators            (void* (* calloc_fn)(size_t, size_t),
                                                      void  (* free_fn)(void*),
-                                                     void* (* realloc_fn)(void*, size_t));
+                                                     void* (* realloc_fn)(void*, size_t, size_t));  //  first old, then new
 
     M3Result            m3_SetTransientAllocators   (void* (* calloc_fn)(size_t, size_t),
                                                      void  (* free_fn)(void*),
-                                                     void* (* realloc_fn)(void*, size_t));
+                                                     void* (* realloc_fn)(void*, size_t, size_t));  //  first old, then new
                                                     
     M3Result            m3_SetMemoryAllocators      (void* (* calloc_fn)(size_t, size_t),
                                                      void  (* free_fn)(void*),
-                                                     void* (* realloc_fn)(void*, size_t));
+                                                     void* (* realloc_fn)(void*, size_t, size_t));  //  first old, then new
 
     void                m3_RewritePointersRuntime   (IM3Runtime runtime,
                                                      uint8_t* base,