diff --git a/functions/inc.js b/functions/inc.js
index aa4d83ab..62d1da2c 100644
--- a/functions/inc.js
+++ b/functions/inc.js
@@ -7,7 +7,10 @@ const inc = (version, release, options, identifier) => {
   }
 
   try {
-    return new SemVer(version, options).inc(release, identifier).version
+    return new SemVer(
+      version instanceof SemVer ? version.version : version,
+      options
+    ).inc(release, identifier).version
   } catch (er) {
     return null
   }