diff --git a/lib/program.js b/lib/program.js
index c80a00d..beae9f2 100644
--- a/lib/program.js
+++ b/lib/program.js
@@ -94,7 +94,7 @@ function Program(options) {
   this.tmuxVersion = (function() {
     if (!self.tmux) return 2;
     try {
-      version = cp.execFileSync('tmux', ['-V'], { encoding: 'utf8' });
+      var version = cp.execFileSync('tmux', ['-V'], { encoding: 'utf8' });
       return +/^tmux ([\d.]+)/i.exec(version.trim().split('\n')[0])[1];
     } catch (e) {
       return 2;