diff --git a/tools/Unix.mk b/tools/Unix.mk
index db56615c759..fbef72124aa 100644
--- a/tools/Unix.mk
+++ b/tools/Unix.mk
@@ -624,7 +624,14 @@ define kconfig_tweak_disable
 	kconfig-tweak --file $1 -u $2
 endef
 else
-  PURGE_MODULE_WARNING  = 2> >(grep -v "warning: the 'modules' option is not supported")
+  KCONFIG_WARNING       = if [ -s kwarning ]; \
+                            then rm kwarning; \
+                              exit 1; \
+                            else \
+                              rm kwarning; \
+                          fi
+  MODULE_WARNING        = "warning: the 'modules' option is not supported"
+  PURGE_MODULE_WARNING  = 2> >(grep -v ${MODULE_WARNING} | tee kwarning) && ${KCONFIG_WARNING}
   KCONFIG_OLDCONFIG     = oldconfig ${PURGE_MODULE_WARNING}
   KCONFIG_OLDDEFCONFIG  = olddefconfig ${PURGE_MODULE_WARNING}
   KCONFIG_MENUCONFIG    = menuconfig ${PURGE_MODULE_WARNING}