diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index 4697e4b59d6f..c18257b0fa72 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -109,7 +109,8 @@ static inline int ddebug_dyndbg_module_param_cb(char *param, char *val,
 						const char *modname)
 {
 	if (strstr(param, "dyndbg")) {
-		pr_warn("dyndbg supported only in "
+		/* avoid pr_warn(), which wants pr_fmt() fully defined */
+		printk(KERN_WARNING "dyndbg param is supported only in "
 			"CONFIG_DYNAMIC_DEBUG builds\n");
 		return 0; /* allow and ignore */
 	}