diff --git a/tools/perf/bash_completion b/tools/perf/bash_completion
index 50540cf..b0cdd12 100644
--- a/tools/perf/bash_completion
+++ b/tools/perf/bash_completion
@@ -11,7 +11,7 @@
 {
 	if [[ "$1" == *:* && "$COMP_WORDBREAKS" == *:* ]]; then
 		# Remove colon-word prefix from COMPREPLY items
-		local colon_word=${1%${1##*:}}
+		local colon_word=${1%"${1##*:}"}
 		local i=${#COMPREPLY[*]}
 		while [[ $((--i)) -ge 0 ]]; do
 			COMPREPLY[$i]=${COMPREPLY[$i]#"$colon_word"}