diff --git a/bash.md b/bash.md
index a25ff354a..d71b56791 100644
--- a/bash.md
+++ b/bash.md
@@ -154,7 +154,7 @@ echo ${STR/foo/bar} # /path/to/bar.cpp
 ```bash
 STR="Hello world"
 echo ${STR:6:5}   # "world"
-echo ${STR:-5:5}  # "world"
+echo ${STR: -5:5}  # "world"
 ```
 
 ```bash