diff --git a/library/pkwrite.c b/library/pkwrite.c
index 6c982ee..a8cbd6b 100644
--- a/library/pkwrite.c
+++ b/library/pkwrite.c
@@ -51,7 +51,7 @@
 #include "mbedtls/platform.h"
 #else
 #include <stdlib.h>
-#define mbedtls_malloc     malloc
+#define mbedtls_calloc    calloc
 #define mbedtls_free       free
 #endif