diff --git a/reactos/lib/sdk/crt/misc/assert.c b/reactos/lib/sdk/crt/misc/assert.c
index cfef25812c3..38c6940e7e4 100644
--- a/reactos/lib/sdk/crt/misc/assert.c
+++ b/reactos/lib/sdk/crt/misc/assert.c
@@ -5,15 +5,68 @@
 #include <stdlib.h>
 #include <signal.h>
 
+static const char formatstr[] = 
+    "Assertion failed!\n\n"
+    "Program: %s\n"
+    "File: %s\n"
+    "Line: %ld\n\n"
+    "Expression: %s\n"
+    "Press Retry to debug the application\n";
+
 
 /*
  * @implemented
  */
-void _assert(const char *msg, const char *file, unsigned line)
+void _assert(const char *exp, const char *file, unsigned line)
 {
-  /* Assertion failed at foo.c line 45: x<y */
-  fprintf(stderr, "Assertion failed at %s line %d: %s\n", file, line, msg);
-  FIXME("Assertion failed at %s line %d: %s\n", file, line, msg);
-  raise(SIGABRT);
-  for(;;); /* eliminate warning by mingw */
+    int (WINAPI *pMessageBoxA)(HWND, LPCTSTR, LPCTSTR, UINT);
+    HMODULE hmodUser32;
+    char achProgram[40];
+    char *pszBuffer;
+    int len;
+    int iResult;
+
+    /* Assertion failed at foo.c line 45: x<y */
+    fprintf(stderr, "Assertion failed at %s line %d: %s\n", file, line, exp);
+    FIXME("Assertion failed at %s line %d: %s\n", file, line, exp);
+
+    /* Get MessageBoxA function pointer */
+    hmodUser32 = LoadLibrary("user32.dll");
+    pMessageBoxA = GetProcAddress(hmodUser32, "MessageBoxA");
+    if (!pMessageBoxA)
+    {
+        abort();
+    }
+
+    /* Get the file name of the module */
+    len = GetModuleFileNameA(NULL, achProgram, 40);
+    
+    /* Calculate full length of the message */
+    len += sizeof(formatstr) + len + strlen(exp) + strlen(file);
+
+    /* Allocate a buffer */
+    pszBuffer = malloc(len + 1);
+
+    /* Format a message */
+    _snprintf(pszBuffer, len, formatstr, achProgram, file, line, exp);
+
+    /* Display a message box */
+    iResult = pMessageBoxA(NULL, 
+                          pszBuffer, 
+                          "ReactOS C Runtime Library",
+                          MB_ABORTRETRYIGNORE | MB_ICONERROR);
+
+    free(pszBuffer);
+
+    /* Does the user want to abort? */
+    if (iResult == IDABORT)
+    {
+        abort();
+    }
+
+    /* Does the user want to debug? */
+    if (iResult == IDRETRY)
+    {
+        __debugbreak();
+    }
 }