diff --git a/lib/internal/process/warning.js b/lib/internal/process/warning.js
index a970b622c89..e367cf1f58b 100644
--- a/lib/internal/process/warning.js
+++ b/lib/internal/process/warning.js
@@ -83,7 +83,7 @@ function setupProcessWarnings() {
       if (isDeprecation && process.noDeprecation) return;
       const trace = process.traceProcessWarnings ||
                     (isDeprecation && process.traceDeprecation);
-      var msg = `${prefix}`;
+      var msg = prefix;
       if (warning.code)
         msg += `[${warning.code}] `;
       if (trace && warning.stack) {