diff --git a/core/main.mk b/core/main.mk
index 7068436..1ca02d1 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -95,12 +95,19 @@
 # and host information.
 include $(BUILD_SYSTEM)/config.mk
 
+relaunch_with_ninja :=
 ifneq ($(USE_NINJA),false)
+ifndef BUILDING_WITH_NINJA
+relaunch_with_ninja := true
+endif
+endif
+
+ifeq ($(relaunch_with_ninja),true)
 # Mark this is a ninja build.
 $(shell mkdir -p $(OUT_DIR) && touch $(OUT_DIR)/ninja_build)
 include build/core/ninja.mk
-else # !USE_NINJA
-ifeq ($(MAKELEVEL),0)
+else # !relaunch_with_ninja
+ifndef BUILDING_WITH_NINJA
 # Remove ninja build mark if it exists.
 $(shell rm -f $(OUT_DIR)/ninja_build)
 endif
@@ -1074,4 +1081,4 @@
 .PHONY: nothing
 nothing:
 	@echo Successfully read the makefiles.
-endif # !USE_NINJA
+endif # !relaunch_with_ninja
diff --git a/core/ninja.mk b/core/ninja.mk
index 2d0af34..b590627 100644
--- a/core/ninja.mk
+++ b/core/ninja.mk
@@ -136,7 +136,7 @@
 .INTERMEDIATE: kati.intermediate
 kati.intermediate: $(KATI) $(MAKEPARALLEL)
 	@echo Running kati to generate build$(KATI_NINJA_SUFFIX).ninja...
-	+$(hide) $(KATI_MAKEPARALLEL) $(KATI) --ninja --ninja_dir=$(PRODUCT_OUT) --ninja_suffix=$(KATI_NINJA_SUFFIX) --regen --ignore_dirty=$(OUT_DIR)/% --ignore_optional_include=$(OUT_DIR)/%.P --detect_android_echo --use_find_emulator -f build/core/main.mk $(or $(KATI_TARGETS),--gen_all_phony_targets) USE_NINJA=false
+	+$(hide) $(KATI_MAKEPARALLEL) $(KATI) --ninja --ninja_dir=$(PRODUCT_OUT) --ninja_suffix=$(KATI_NINJA_SUFFIX) --regen --ignore_dirty=$(OUT_DIR)/% --ignore_optional_include=$(OUT_DIR)/%.P --detect_android_echo --use_find_emulator -f build/core/main.mk $(or $(KATI_TARGETS),--gen_all_phony_targets) BUILDING_WITH_NINJA=true
 
 KATI_CXX := $(CLANG_CXX) $(CLANG_HOST_GLOBAL_CFLAGS) $(CLANG_HOST_GLOBAL_CPPFLAGS)
 KATI_LD := $(CLANG_CXX) $(CLANG_HOST_GLOBAL_LDFLAGS)