diff --git a/tools/grib_options.c b/tools/grib_options.c
index 5557a43cb..a76ff7758 100644
--- a/tools/grib_options.c
+++ b/tools/grib_options.c
@@ -402,7 +402,7 @@ int grib_process_runtime_options(grib_context* context, int argc, char** argv, g
     return GRIB_SUCCESS;
 }
 
-char* grib_options_get_help(char* id)
+const char* grib_options_get_help(const char* id)
 {
     int i      = 0;
     char msg[] = "ERROR: help not found for option ";
@@ -424,7 +424,7 @@ char* grib_options_get_help(char* id)
     return err;
 }
 
-char* grib_options_get_args(char* id)
+const char* grib_options_get_args(const char* id)
 {
     int i        = 0;
     char empty[] = "";
diff --git a/tools/grib_tools.h b/tools/grib_tools.h
index 1ea85e216..e877aa52c 100644
--- a/tools/grib_tools.h
+++ b/tools/grib_tools.h
@@ -189,8 +189,8 @@ int grib_options_on(const char* id);
 int grib_options_get(int argc, char** argv);
 int grib_options_get_values(int argc, char** argv, int values_required, int default_type, grib_values values[], int* n, int* optind);
 int grib_tool(int argc, char** argv);
-char* grib_options_get_help(char* id);
-char* grib_options_get_args(char* id);
+const char* grib_options_get_help(const char* id);
+const char* grib_options_get_args(const char* id);
 int grib_options_command_line(const char* id);
 void usage(void);
 void usage_doxygen(void);