diff --git a/core/Makefile b/core/Makefile
index 7fa7a6be40..6602a2910c 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -91,9 +91,7 @@ all_copied_headers: $(ALL_COPIED_HEADERS)
 
 ifdef has_dup_copy_headers
   has_dup_copy_headers :=
-  ifneq ($(BUILD_BROKEN_DUP_COPY_HEADERS),true)
-    $(error duplicate header copies are no longer allowed. For more information about headers, see: https://android.googlesource.com/platform/build/soong/+/master/docs/best_practices.md#headers)
-  endif
+  $(error duplicate header copies are no longer allowed. For more information about headers, see: https://android.googlesource.com/platform/build/soong/+/master/docs/best_practices.md#headers)
 endif
 
 # -----------------------------------------------------------------
diff --git a/core/board_config.mk b/core/board_config.mk
index e4b88cb601..bfce087f85 100644
--- a/core/board_config.mk
+++ b/core/board_config.mk
@@ -86,9 +86,7 @@ _board_strip_readonly_list += $(_dynamic_partitions_var_list)
 
 _build_broken_var_list := \
   BUILD_BROKEN_ANDROIDMK_EXPORTS \
-  BUILD_BROKEN_DUP_COPY_HEADERS \
   BUILD_BROKEN_DUP_RULES \
-  BUILD_BROKEN_PHONY_TARGETS \
   BUILD_BROKEN_ENG_DEBUG_TAGS \
   BUILD_BROKEN_USES_NETWORK \
 
diff --git a/core/config.mk b/core/config.mk
index 16cd37625f..386c64e74d 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -95,6 +95,8 @@ $(KATI_obsolete_var TARGET_ANDROID_FILESYSTEM_CONFIG_H,Use TARGET_FS_CONFIG_GEN
 $(KATI_deprecated_var USER,Use BUILD_USERNAME instead. See $(CHANGES_URL)#USER)
 $(KATI_obsolete_var TARGET_ROOT_OUT_SBIN,/sbin has been removed, use /system/bin instead)
 $(KATI_obsolete_var TARGET_ROOT_OUT_SBIN_UNSTRIPPED,/sbin has been removed, use /system/bin instead)
+$(KATI_obsolete_var BUILD_BROKEN_PHONY_TARGETS)
+$(KATI_obsolete_var BUILD_BROKEN_DUP_COPY_HEADERS)
 
 # This is marked as obsolete in envsetup.mk after reading the BoardConfig.mk
 $(KATI_deprecate_export It is a global setting. See $(CHANGES_URL)#export_keyword)