diff --git a/library/lms.c b/library/lms.c
index 321e51a..b460353 100644
--- a/library/lms.c
+++ b/library/lms.c
@@ -736,7 +736,7 @@
     if ( MBEDTLS_LMS_SIG_LEN(ctx->params.type, ctx->params.otstype)
          < SIG_OTS_SIG_OFFSET )
     {
-        return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
+        return ( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
     }
 
     ret = mbedtls_lmots_sign( &ctx->ots_private_keys[q_leaf_identifier],