diff --git a/lib/node/config.js b/lib/node/config.js
index 51127aba..50acda61 100644
--- a/lib/node/config.js
+++ b/lib/node/config.js
@@ -956,7 +956,7 @@ Config.prototype.parseEnv = function parseEnv(env) {
 
     assert(typeof value === 'string');
 
-    if (key.indexOf(prefix) === 0)
+    if (key.indexOf(prefix) !== 0)
       continue;
 
     key = key.substring(prefix.length);