diff --git a/library/rsa.c b/library/rsa.c
index e3ec056..36f487f 100644
--- a/library/rsa.c
+++ b/library/rsa.c
@@ -1896,9 +1896,13 @@
     memcpy( sig, sig_try, ctx->len );
 
 cleanup:
+    mbedtls_platform_zeroize( sig_try, ctx->len );
+    mbedtls_platform_zeroize( verif, ctx->len );
     mbedtls_free( sig_try );
     mbedtls_free( verif );
 
+    if( ret != 0 )
+        memset( sig, '!', ctx->len );
     return( ret );
 }
 #endif /* MBEDTLS_PKCS1_V15 */