diff --git a/MemoryModule.c b/MemoryModule.c
index cabaabb..d8d3f3a 100644
--- a/MemoryModule.c
+++ b/MemoryModule.c
@@ -56,6 +56,8 @@ typedef struct {
     BOOL initialized;
     BOOL isDLL;
     BOOL isRelocated;
+    CustomAllocFunc alloc;
+    CustomFreeFunc free;
     CustomLoadLibraryFunc loadLibrary;
     CustomGetProcAddressFunc getProcAddress;
     CustomFreeLibraryFunc freeLibrary;
@@ -115,10 +117,11 @@ CopySections(const unsigned char *data, size_t size, PIMAGE_NT_HEADERS old_heade
             // uninitialized data
             section_size = old_headers->OptionalHeader.SectionAlignment;
             if (section_size > 0) {
-                dest = (unsigned char *)VirtualAlloc(codeBase + section->VirtualAddress,
+                dest = (unsigned char *)module->alloc(codeBase + section->VirtualAddress,
                     section_size,
                     MEM_COMMIT,
-                    PAGE_READWRITE);
+                    PAGE_READWRITE,
+                    module->userdata);
                 if (dest == NULL) {
                     return FALSE;
                 }
@@ -139,10 +142,11 @@ CopySections(const unsigned char *data, size_t size, PIMAGE_NT_HEADERS old_heade
         }
 
         // commit memory block and copy data from dll
-        dest = (unsigned char *)VirtualAlloc(codeBase + section->VirtualAddress,
+        dest = (unsigned char *)module->alloc(codeBase + section->VirtualAddress,
                             section->SizeOfRawData,
                             MEM_COMMIT,
-                            PAGE_READWRITE);
+                            PAGE_READWRITE,
+                            module->userdata);
         if (dest == NULL) {
             return FALSE;
         }
@@ -202,7 +206,7 @@ FinalizeSection(PMEMORYMODULE module, PSECTIONFINALIZEDATA sectionData) {
              (sectionData->size % module->pageSize) == 0)
            ) {
             // Only allowed to decommit whole pages
-            VirtualFree(sectionData->address, sectionData->size, MEM_DECOMMIT);
+            module->free(sectionData->address, sectionData->size, MEM_DECOMMIT, module->userdata);
         }
         return TRUE;
     }
@@ -429,6 +433,18 @@ BuildImportTable(PMEMORYMODULE module)
     return result;
 }
 
+LPVOID MemoryDefaultAlloc(LPVOID address, SIZE_T size, DWORD allocationType, DWORD protect, void* userdata)
+{
+	UNREFERENCED_PARAMETER(userdata);
+	return VirtualAlloc(address, size, allocationType, protect);
+}
+
+BOOL MemoryDefaultFree(LPVOID lpAddress, SIZE_T dwSize, DWORD dwFreeType, void* userdata)
+{
+	UNREFERENCED_PARAMETER(userdata);
+	return VirtualFree(lpAddress, dwSize, dwFreeType);
+}
+
 HCUSTOMMODULE MemoryDefaultLoadLibrary(LPCSTR filename, void *userdata)
 {
     HMODULE result;
@@ -455,10 +471,12 @@ void MemoryDefaultFreeLibrary(HCUSTOMMODULE module, void *userdata)
 
 HMEMORYMODULE MemoryLoadLibrary(const void *data, size_t size)
 {
-    return MemoryLoadLibraryEx(data, size, MemoryDefaultLoadLibrary, MemoryDefaultGetProcAddress, MemoryDefaultFreeLibrary, NULL);
+    return MemoryLoadLibraryEx(data, size, MemoryDefaultAlloc, MemoryDefaultFree, MemoryDefaultLoadLibrary, MemoryDefaultGetProcAddress, MemoryDefaultFreeLibrary, NULL);
 }
 
 HMEMORYMODULE MemoryLoadLibraryEx(const void *data, size_t size,
+    CustomAllocFunc allocMemory,
+    CustomFreeFunc freeMemory,
     CustomLoadLibraryFunc loadLibrary,
     CustomGetProcAddressFunc getProcAddress,
     CustomFreeLibraryFunc freeLibrary,
@@ -535,17 +553,19 @@ HMEMORYMODULE MemoryLoadLibraryEx(const void *data, size_t size,
     // reserve memory for image of library
     // XXX: is it correct to commit the complete memory region at once?
     //      calling DllEntry raises an exception if we don't...
-    code = (unsigned char *)VirtualAlloc((LPVOID)(old_header->OptionalHeader.ImageBase),
+    code = (unsigned char *)allocMemory((LPVOID)(old_header->OptionalHeader.ImageBase),
         alignedImageSize,
         MEM_RESERVE | MEM_COMMIT,
-        PAGE_READWRITE);
+        PAGE_READWRITE,
+        userdata);
 
     if (code == NULL) {
         // try to allocate memory at arbitrary position
-        code = (unsigned char *)VirtualAlloc(NULL,
+        code = (unsigned char *)allocMemory(NULL,
             alignedImageSize,
             MEM_RESERVE | MEM_COMMIT,
-            PAGE_READWRITE);
+            PAGE_READWRITE,
+            userdata);
         if (code == NULL) {
             SetLastError(ERROR_OUTOFMEMORY);
             return NULL;
@@ -554,13 +574,15 @@ HMEMORYMODULE MemoryLoadLibraryEx(const void *data, size_t size,
 
     result = (PMEMORYMODULE)HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(MEMORYMODULE));
     if (result == NULL) {
-        VirtualFree(code, 0, MEM_RELEASE);
+        freeMemory(code, 0, MEM_RELEASE, userdata);
         SetLastError(ERROR_OUTOFMEMORY);
         return NULL;
     }
 
     result->codeBase = code;
     result->isDLL = (old_header->FileHeader.Characteristics & IMAGE_FILE_DLL) != 0;
+    result->alloc = allocMemory;
+    result->free = freeMemory;
     result->loadLibrary = loadLibrary;
     result->getProcAddress = getProcAddress;
     result->freeLibrary = freeLibrary;
@@ -572,10 +594,11 @@ HMEMORYMODULE MemoryLoadLibraryEx(const void *data, size_t size,
     }
 
     // commit memory for headers
-    headers = (unsigned char *)VirtualAlloc(code,
+    headers = (unsigned char *)allocMemory(code,
         old_header->OptionalHeader.SizeOfHeaders,
         MEM_COMMIT,
-        PAGE_READWRITE);
+        PAGE_READWRITE,
+        userdata);
 
     // copy PE header to code
     memcpy(headers, dos_header, old_header->OptionalHeader.SizeOfHeaders);
@@ -724,7 +747,7 @@ void MemoryFreeLibrary(HMEMORYMODULE mod)
 
     if (module->codeBase != NULL) {
         // release memory of library
-        VirtualFree(module->codeBase, 0, MEM_RELEASE);
+        module->free(module->codeBase, 0, MEM_RELEASE, module->userdata);
     }
 
     HeapFree(GetProcessHeap(), 0, module);
diff --git a/MemoryModule.h b/MemoryModule.h
index d8f3938..a728f6b 100644
--- a/MemoryModule.h
+++ b/MemoryModule.h
@@ -39,6 +39,8 @@ typedef void *HCUSTOMMODULE;
 extern "C" {
 #endif
 
+typedef LPVOID (*CustomAllocFunc)(LPVOID, SIZE_T, DWORD, DWORD, void*);
+typedef BOOL (*CustomFreeFunc)(LPVOID, SIZE_T, DWORD, void*);
 typedef HCUSTOMMODULE (*CustomLoadLibraryFunc)(LPCSTR, void *);
 typedef FARPROC (*CustomGetProcAddressFunc)(HCUSTOMMODULE, LPCSTR, void *);
 typedef void (*CustomFreeLibraryFunc)(HCUSTOMMODULE, void *);
@@ -58,6 +60,8 @@ HMEMORYMODULE MemoryLoadLibrary(const void *, size_t);
  * Dependencies will be resolved using passed callback methods.
  */
 HMEMORYMODULE MemoryLoadLibraryEx(const void *, size_t,
+    CustomAllocFunc,
+    CustomFreeFunc,
     CustomLoadLibraryFunc,
     CustomGetProcAddressFunc,
     CustomFreeLibraryFunc,
@@ -117,6 +121,22 @@ int MemoryLoadString(HMEMORYMODULE, UINT, LPTSTR, int);
  */
 int MemoryLoadStringEx(HMEMORYMODULE, UINT, LPTSTR, int, WORD);
 
+/**
+* Default implementation of CustomAllocFunc that calls VirtualAlloc
+* internally to allocate memory for a library
+*
+* This is the default as used by MemoryLoadLibrary.
+*/
+LPVOID MemoryDefaultAlloc(LPVOID, SIZE_T, DWORD, DWORD, void *);
+
+/**
+* Default implementation of CustomFreeFunc that calls VirtualFree
+* internally to free the memory used by a library
+*
+* This is the default as used by MemoryLoadLibrary.
+*/
+BOOL MemoryDefaultFree(LPVOID, SIZE_T, DWORD, void *);
+
 /**
  * Default implementation of CustomLoadLibraryFunc that calls LoadLibraryA
  * internally to load an additional libary.
diff --git a/example/DllLoader/DllLoader.cpp b/example/DllLoader/DllLoader.cpp
index 4ff1a20..973f5b4 100644
--- a/example/DllLoader/DllLoader.cpp
+++ b/example/DllLoader/DllLoader.cpp
@@ -46,12 +46,48 @@ void LoadFromFile(void)
     FreeLibrary(handle);
 }
 
+void* ReadLibrary(long* pSize) {
+    long read;
+    void* result;
+    FILE* fp;
+
+    fp = _tfopen(DLL_FILE, _T("rb"));
+    if (fp == NULL)
+    {
+        _tprintf(_T("Can't open DLL file \"%s\"."), DLL_FILE);
+        return NULL;
+    }
+
+    fseek(fp, 0, SEEK_END);
+    *pSize = ftell(fp);
+    if (*pSize < 0)
+    {
+        fclose(fp);
+        return NULL;
+    }
+
+    result = (unsigned char *)malloc(*pSize);
+    if (result == NULL)
+    {
+        return NULL;
+    }
+
+    fseek(fp, 0, SEEK_SET);
+    read = fread(result, 1, *pSize, fp);
+    fclose(fp);
+    if (read != static_cast<size_t>(*pSize))
+    {
+        free(result);
+        return NULL;
+    }
+
+    return result;
+}
+
 void LoadFromMemory(void)
 {
-    FILE *fp;
-    unsigned char *data=NULL;
+    void *data;
     long size;
-    size_t read;
     HMEMORYMODULE handle;
     addNumberProc addNumber;
     HMEMORYRSRC resourceInfo;
@@ -59,23 +95,12 @@ void LoadFromMemory(void)
     LPVOID resourceData;
     TCHAR buffer[100];
 
-    fp = _tfopen(DLL_FILE, _T("rb"));
-    if (fp == NULL)
+    data = ReadLibrary(&size);
+    if (data == NULL)
     {
-        _tprintf(_T("Can't open DLL file \"%s\"."), DLL_FILE);
-        goto exit;
+        return;
     }
 
-    fseek(fp, 0, SEEK_END);
-    size = ftell(fp);
-    assert(size >= 0);
-    data = (unsigned char *)malloc(size);
-    assert(data != NULL);
-    fseek(fp, 0, SEEK_SET);
-    read = fread(data, 1, size, fp);
-    assert(read == static_cast<size_t>(size));
-    fclose(fp);
-
     handle = MemoryLoadLibrary(data, size);
     if (handle == NULL)
     {
@@ -105,11 +130,161 @@ void LoadFromMemory(void)
     free(data);
 }
 
+#define MAX_CALLS 20
+
+struct CallList {
+    int current_alloc_call, current_free_call;
+    CustomAllocFunc alloc_calls[MAX_CALLS];
+    CustomFreeFunc free_calls[MAX_CALLS];
+};
+
+LPVOID MemoryFailingAlloc(LPVOID address, SIZE_T size, DWORD allocationType, DWORD protect, void* userdata)
+{
+    UNREFERENCED_PARAMETER(address);
+    UNREFERENCED_PARAMETER(size);
+    UNREFERENCED_PARAMETER(allocationType);
+    UNREFERENCED_PARAMETER(protect);
+    UNREFERENCED_PARAMETER(userdata);
+    return NULL;
+}
+
+LPVOID MemoryMockAlloc(LPVOID address, SIZE_T size, DWORD allocationType, DWORD protect, void* userdata)
+{
+    CallList* calls = (CallList*)userdata;
+    CustomAllocFunc current_func = calls->alloc_calls[calls->current_alloc_call++];
+    assert(current_func != NULL);
+    return current_func(address, size, allocationType, protect, NULL);
+}
+
+BOOL MemoryMockFree(LPVOID lpAddress, SIZE_T dwSize, DWORD dwFreeType, void* userdata)
+{
+    CallList* calls = (CallList*)userdata;
+    CustomFreeFunc current_func = calls->free_calls[calls->current_free_call++];
+    assert(current_func != NULL);
+    return current_func(lpAddress, dwSize, dwFreeType, NULL);
+}
+
+void InitFuncs(void** funcs, va_list args) {
+    for (int i = 0; ; i++) {
+        assert(i < MAX_CALLS);
+        funcs[i] = va_arg(args, void*);
+        if (funcs[i] == NULL) break;
+    }
+}
+
+void InitAllocFuncs(CallList* calls, ...) {
+    va_list args;
+    va_start(args, calls);
+    InitFuncs((void**)calls->alloc_calls, args);
+    va_end(args);
+    calls->current_alloc_call = 0;
+}
+
+void InitFreeFuncs(CallList* calls, ...) {
+    va_list args;
+    va_start(args, calls);
+    InitFuncs((void**)calls->free_calls, args);
+    va_end(args);
+    calls->current_free_call = 0;
+}
+
+void InitFreeFunc(CallList* calls, CustomFreeFunc freeFunc) {
+	for (int i = 0; i < MAX_CALLS; i++) {
+		calls->free_calls[i] = freeFunc;
+	}
+	calls->current_free_call = 0;
+}
+
+void TestFailingAllocation(void *data, long size) {
+    CallList expected_calls;
+    HMEMORYMODULE handle;
+
+    InitAllocFuncs(&expected_calls, MemoryFailingAlloc, MemoryFailingAlloc, NULL);
+    InitFreeFuncs(&expected_calls, NULL);
+
+    handle = MemoryLoadLibraryEx(
+        data, size, MemoryMockAlloc, MemoryMockFree, MemoryDefaultLoadLibrary,
+        MemoryDefaultGetProcAddress, MemoryDefaultFreeLibrary, &expected_calls);
+
+    assert(handle == NULL);
+    assert(GetLastError() == ERROR_OUTOFMEMORY);
+    assert(expected_calls.current_free_call == 0);
+
+    MemoryFreeLibrary(handle);
+    assert(expected_calls.current_free_call == 0);
+}
+
+void TestCleanupAfterFailingAllocation(void *data, long size) {
+    CallList expected_calls;
+    HMEMORYMODULE handle;
+    int free_calls_after_loading;
+
+    InitAllocFuncs(&expected_calls,
+        MemoryDefaultAlloc,
+        MemoryDefaultAlloc,
+        MemoryDefaultAlloc,
+        MemoryDefaultAlloc,
+        MemoryFailingAlloc,
+        NULL);
+    InitFreeFuncs(&expected_calls, MemoryDefaultFree, NULL);
+
+    handle = MemoryLoadLibraryEx(
+        data, size, MemoryMockAlloc, MemoryMockFree, MemoryDefaultLoadLibrary,
+        MemoryDefaultGetProcAddress, MemoryDefaultFreeLibrary, &expected_calls);
+
+    free_calls_after_loading = expected_calls.current_free_call;
+
+    MemoryFreeLibrary(handle);
+    assert(expected_calls.current_free_call == free_calls_after_loading);
+}
+
+void TestFreeAfterDefaultAlloc(void *data, long size) {
+    CallList expected_calls;
+    HMEMORYMODULE handle;
+    int free_calls_after_loading;
+
+	// Note: free might get called internally multiple times
+    InitFreeFunc(&expected_calls, MemoryDefaultFree);
+
+    handle = MemoryLoadLibraryEx(
+        data, size, MemoryDefaultAlloc, MemoryMockFree, MemoryDefaultLoadLibrary,
+        MemoryDefaultGetProcAddress, MemoryDefaultFreeLibrary, &expected_calls);
+
+    assert(handle != NULL);
+    free_calls_after_loading = expected_calls.current_free_call;
+
+    MemoryFreeLibrary(handle);
+    assert(expected_calls.current_free_call == free_calls_after_loading + 1);
+}
+
+void TestCustomAllocAndFree(void)
+{
+    void *data;
+    long size;
+
+    data = ReadLibrary(&size);
+    if (data == NULL)
+    {
+        return;
+    }
+
+    _tprintf(_T("Test MemoryLoadLibraryEx after initially failing allocation function\n"));
+    TestFailingAllocation(data, size);
+    _tprintf(_T("Test cleanup after MemoryLoadLibraryEx with failing allocation function\n"));
+    TestCleanupAfterFailingAllocation(data, size);
+    _tprintf(_T("Test custom free function after MemoryLoadLibraryEx\n"));
+    TestFreeAfterDefaultAlloc(data, size);
+
+    free(data);
+}
+
 int main()
 {
     LoadFromFile();
     printf("\n\n");
     LoadFromMemory();
+    printf("\n\n");
+    TestCustomAllocAndFree();
     return 0;
 }