diff --git a/basei3/Dockerfile b/basei3/Dockerfile
index 14caa03..88918ee 100644
--- a/basei3/Dockerfile
+++ b/basei3/Dockerfile
@@ -3,7 +3,7 @@ FROM alpine/base
 USER root
 
 # X session environment variable
-ENV STARTXBIN i3
+ENV STARTXBIN=i3
 
 # Run
 RUN apk add --no-cache \