diff --git a/src/shell-doc-system.c b/src/shell-doc-system.c
index c58b34b1b..ecb99736e 100644
--- a/src/shell-doc-system.c
+++ b/src/shell-doc-system.c
@@ -255,7 +255,12 @@ shell_doc_system_open (ShellDocSystem *system,
   else
     {
       char *app_name;
-      char *app_exec, *app_exec_quoted;
+#if GTK_MINOR_VERSION >= 18
+      const char *app_exec;
+#else
+      char *app_exec;
+#endif
+      char *app_exec_quoted;
       guint count;
       time_t time;