diff --git a/tommath_private.h b/tommath_private.h
index 56debfc..64a8794 100644
--- a/tommath_private.h
+++ b/tommath_private.h
@@ -30,14 +30,14 @@ extern "C" {
 #ifndef XMALLOC
 /* default to libc stuff */
 #   define XMALLOC(size)                   malloc(size)
-#   define XFREE(mem, size)                free(mem)
 #   define XREALLOC(mem, oldsize, newsize) realloc(mem, newsize)
-#   define XCALLOC   calloc
+#   define XCALLOC(nmemb, size)            calloc(nmemb, size)
+#   define XFREE(mem, size)                free(mem)
 #else
 /* prototypes for our heap functions */
 extern void *XMALLOC(size_t size);
 extern void *XREALLOC(void *mem, size_t oldsize, size_t newsize);
-extern void *XCALLOC(size_t n, size_t s);
+extern void *XCALLOC(size_t nmemb, size_t size);
 extern void XFREE(void *mem, size_t size);
 #endif