diff --git a/library/rsa.c b/library/rsa.c
index fba68dd..3cb92f4 100644
--- a/library/rsa.c
+++ b/library/rsa.c
@@ -529,7 +529,8 @@
     olen = ctx->len;
     hlen = mbedtls_md_get_size( md_info );
 
-    if( olen < ilen + 2 * hlen + 2 )
+    // first comparison checks for overflow
+    if( ilen + 2 * hlen + 2 < ilen || olen < ilen + 2 * hlen + 2 )
         return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
 
     memset( output, 0, olen );
@@ -594,8 +595,9 @@
         return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
 
     olen = ctx->len;
-
-    if( olen < ilen + 11 )
+    
+    // first comparison checks for overflow
+    if( ilen + 11 < ilen || olen < ilen + 11 )
         return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
 
     nb_pad = olen - 3 - ilen;