diff --git a/lib/prepare.js b/lib/prepare.js
index 219109b..2499aa6 100644
--- a/lib/prepare.js
+++ b/lib/prepare.js
@@ -45,7 +45,7 @@ const bundleInstall = async ({
 };
 
 const buildGem = async ({
-  gemspec,
+  gemSpec,
   gemName,
   version,
   cwd,
@@ -58,7 +58,7 @@ const buildGem = async ({
 
   logger.log("Building gem `%s`", gemFile);
 
-  const buildResult = execa("gem", ["build", gemspec], { cwd, env });
+  const buildResult = execa("gem", ["build", gemSpec], { cwd, env });
 
   buildResult.stdout.pipe(stdout, { end: false });