diff --git a/include/polarssl/cipher.h b/include/polarssl/cipher.h
index 853c7e6..5ae25c1 100644
--- a/include/polarssl/cipher.h
+++ b/include/polarssl/cipher.h
@@ -379,7 +379,7 @@
         return 0;
 
     if( ctx->iv_size != 0 )
-        return ctx->iv_size;
+        return (int) ctx->iv_size;
 
     return ctx->cipher_info->iv_size;
 }