diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index a0b4fb58201c..ddd644bd032d 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -101,7 +101,9 @@ else ifeq ($(KBUILD_CHECKSRC),2)
 endif
 
 ifneq ($(KBUILD_EXTRA_WARN),)
-  cmd_checkdoc = $(srctree)/scripts/kernel-doc -none $(KDOCFLAGS) $<
+  cmd_checkdoc = $(srctree)/scripts/kernel-doc -none $(KDOCFLAGS) \
+        $(if $(findstring 2, $(KBUILD_EXTRA_WARN)), -Wall) \
+        $<
 endif
 
 # Compile C sources (.c)