diff --git a/etc/guix-install.sh b/etc/guix-install.sh
index d3f80d1a35..05e2ef8157 100755
--- a/etc/guix-install.sh
+++ b/etc/guix-install.sh
@@ -87,6 +87,7 @@ _debug()
 chk_require()
 { # Check that every required command is available.
     declare -a warn
+    local c
 
     _debug "--- [ $FUNCNAME ] ---"