diff --git a/lib/parse.js b/lib/parse.js
index 8fd8ff4..0bae4f4 100644
--- a/lib/parse.js
+++ b/lib/parse.js
@@ -1004,7 +1004,9 @@ parse.fastpaths = (input, options) => {
     throw new SyntaxError(`Input length: ${len}, exceeds maximum allowed length: ${max}`);
   }
 
-  input = REPLACEMENTS[input] || input;
+  if (REPLACEMENTS.hasOwnProperty(input)) {
+    input = REPLACEMENTS[input];
+  }
 
   // create constants based on platform, for windows or posix
   const {