diff --git a/etc/rally.bash_completion b/etc/rally.bash_completion
index 8bb8ef0fc3..565c8040ec 100644
--- a/etc/rally.bash_completion
+++ b/etc/rally.bash_completion
@@ -50,8 +50,9 @@ _rally()
 
 
     for OPT in ${!OPTS[*]} ; do
-        CMDSUB=(${OPT//_/ })
-        SUBCOMMANDS[${CMDSUB[0]}]+="${CMDSUB[1]} "
+        CMD=${OPT%%_*}
+        CMDSUB=${OPT#*_}
+        SUBCOMMANDS[${CMD}]+="${CMDSUB} "
     done
 
     COMMANDS="${!SUBCOMMANDS[*]}"
diff --git a/rally/cmd/cliutils.py b/rally/cmd/cliutils.py
index 4740cbb411..6f645bc646 100644
--- a/rally/cmd/cliutils.py
+++ b/rally/cmd/cliutils.py
@@ -445,8 +445,9 @@ _rally()
 %(data)s
 
     for OPT in ${!OPTS[*]} ; do
-        CMDSUB=(${OPT//_/ })
-        SUBCOMMANDS[${CMDSUB[0]}]+="${CMDSUB[1]} "
+        CMD=${OPT%%%%_*}
+        CMDSUB=${OPT#*_}
+        SUBCOMMANDS[${CMD}]+="${CMDSUB} "
     done
 
     COMMANDS="${!SUBCOMMANDS[*]}"
@@ -489,4 +490,4 @@ complete -F _rally rally
 
             completion.append("""    OPTS["{cat}_{cmd}"]="{args}"\n""".format(
                     cat=category, cmd=name, args=args))
-    return bash_data % {"data": "".join(sorted(completion))}
\ No newline at end of file
+    return bash_data % {"data": "".join(sorted(completion))}