--- a/make/test/JtregNativeJdk.gmk	Thu Mar 15 19:30:58 2018 +0100
+++ b/make/test/JtregNativeJdk.gmk	Thu Mar 15 19:33:04 2018 +0100
@@ -41,23 +41,17 @@
 # Targets for building the native tests themselves.
 ################################################################################
 
-# Add more directories here when needed.
-BUILD_JDK_JTREG_NATIVE_SRC += \
-    $(TOPDIR)/test/jdk/native_sanity \
-    $(TOPDIR)/test/jdk/java/lang/ClassLoader/nativeLibrary \
-    $(TOPDIR)/test/jdk/java/lang/String/nativeEncoding \
-    #
-
-ifneq ($(OPENJDK_TARGET_OS), windows)
-  BUILD_JDK_JTREG_NATIVE_SRC += $(TOPDIR)/test/jdk/java/nio/channels/FileChannel/directio
-  BUILD_JDK_JTREG_NATIVE_SRC += $(TOPDIR)/test/jdk/java/nio/channels/spi/SelectorProvider/inheritedChannel
-endif
+# This might have been added to by a custom extension.
+BUILD_JDK_JTREG_NATIVE_SRC += $(TOPDIR)/test/jdk
 
 BUILD_JDK_JTREG_OUTPUT_DIR := $(OUTPUTDIR)/support/test/jdk/jtreg/native
 
 BUILD_JDK_JTREG_IMAGE_DIR := $(TEST_IMAGE_DIR)/jdk/jtreg
 
+# Platform specific setup
 ifeq ($(OPENJDK_TARGET_OS), windows)
+  BUILD_JDK_JTREG_EXCLUDE += libDirectIO.c libInheritedChannel.c
+
   WIN_LIB_JAVA := $(SUPPORT_OUTPUTDIR)/native/java.base/libjava/java.lib
   BUILD_JDK_JTREG_LIBRARIES_LIBS_libstringPlatformChars := $(WIN_LIB_JAVA)
 else
@@ -74,17 +68,18 @@
     TYPE := LIBRARY, \
     SOURCE_DIRS := $(BUILD_JDK_JTREG_NATIVE_SRC), \
     OUTPUT_DIR := $(BUILD_JDK_JTREG_OUTPUT_DIR), \
+    EXCLUDE := $(BUILD_JDK_JTREG_EXCLUDE), \
 ))
 
 $(eval $(call SetupTestFilesCompilation, BUILD_JDK_JTREG_EXECUTABLES, \
     TYPE := PROGRAM, \
     SOURCE_DIRS := $(BUILD_JDK_JTREG_NATIVE_SRC), \
     OUTPUT_DIR := $(BUILD_JDK_JTREG_OUTPUT_DIR), \
+    EXCLUDE := $(BUILD_JDK_JTREG_EXCLUDE), \
 ))
 
 build-test-jdk-jtreg-native: $(BUILD_JDK_JTREG_LIBRARIES) $(BUILD_JDK_JTREG_EXECUTABLES)
 
-
 ################################################################################
 # Targets for building test-image.
 ################################################################################