diff --git a/docs/cli-completion b/docs/cli-completion
index 3e50a6b..116f74e 100644
--- a/docs/cli-completion
+++ b/docs/cli-completion
@@ -18,11 +18,12 @@ _cli.php()
     EXPERT="-expert"
     unset COMP_WORDS[1]
     COMP_WORDS=("${COMP_WORDS[@]}")
-    COMP_CWORD=${COMP_CWORD}-1
+    COMP_CWORD=$((${COMP_CWORD}-1))
   else
     EXPERT=""
   fi
 
+echo "COMP_CWORD=$COMP_CWORD" >> /tmp/debug
   cur="${COMP_WORDS[COMP_CWORD]}"
   prev="${COMP_WORDS[COMP_CWORD-1]}"
   ante="${COMP_WORDS[COMP_CWORD-2]}"