diff --git a/tests/list_all_keys.sh b/tests/list_all_keys.sh
index 573d166d6..78ee26631 100755
--- a/tests/list_all_keys.sh
+++ b/tests/list_all_keys.sh
@@ -32,7 +32,7 @@ cat >keys <<EOF
 %{
 #include "grib_api_internal.h"
 %}
-struct grib_keys_hash { char* name; int id;};
+struct grib_keys_hash { const char* name; int id;};
 %%
 EOF
 cat tmp$$ | sort | uniq | awk 'BEGIN{x=0;}{print $1","++x}' >> keys