diff --git a/library/rsa.c b/library/rsa.c
index bd97d521b8..4daa5b310d 100644
--- a/library/rsa.c
+++ b/library/rsa.c
@@ -574,7 +574,7 @@ static int mgf_mask( unsigned char *dst, size_t dlen, unsigned char *src,
     unsigned char *p;
     unsigned int hlen;
     size_t i, use_len;
-    int ret;
+    int ret = 0;
 
     memset( mask, 0, MBEDTLS_MD_MAX_SIZE );
     memset( counter, 0, 4 );