diff --git a/mysys/md5.c b/mysys/md5.c
index 7179359d213..655befa546a 100644
--- a/mysys/md5.c
+++ b/mysys/md5.c
@@ -176,7 +176,7 @@ my_MD5Final (unsigned char digest[16], my_MD5Context *ctx)
   putu32(ctx->buf[1], digest + 4);
   putu32(ctx->buf[2], digest + 8);
   putu32(ctx->buf[3], digest + 12);
-  memset(ctx, 0, sizeof(ctx));	/* In case it's sensitive */
+  memset(ctx, 0, sizeof(*ctx));	/* In case it's sensitive */
 }
 
 #ifndef ASM_MD5