diff --git a/core/cxx_stl_setup.mk b/core/cxx_stl_setup.mk
index 4f41daa..0f574d2 100644
--- a/core/cxx_stl_setup.mk
+++ b/core/cxx_stl_setup.mk
@@ -4,16 +4,14 @@
 ## Output variables: My_cflags, my_c_includes, my_shared_libraries, etc.
 #############################################################
 
-# Only around for development purposes. Will be removed soon.
-my_libcxx_is_default := false
-
 # Select the appropriate C++ STL
 ifeq ($(strip $(LOCAL_CXX_STL)),default)
     ifndef LOCAL_SDK_VERSION
-        ifeq ($(strip $(my_libcxx_is_default)),true)
-            # Platform code. Select the appropriate STL.
+        # Platform code. Select the appropriate STL.
+        ifndef USE_MINGW
             my_cxx_stl := libc++
         else
+            # libc++ is not supported on mingw.
             my_cxx_stl := libstdc++
         endif
     else
diff --git a/core/host_test_internal.mk b/core/host_test_internal.mk
index 8611c4b..072e5e0 100644
--- a/core/host_test_internal.mk
+++ b/core/host_test_internal.mk
@@ -12,10 +12,10 @@
 LOCAL_CFLAGS += -DGTEST_HAS_STD_STRING -O0 -g
 LOCAL_C_INCLUDES +=  external/gtest/include
 
-my_test_libcxx := false
-ifeq (,$(TARGET_BUILD_APPS))
-ifneq ($(filter $(strip $(LOCAL_CXX_STL)),libc++ libc++_static),)
 my_test_libcxx := true
+ifeq (,$(TARGET_BUILD_APPS))
+ifneq ($(filter $(strip $(LOCAL_CXX_STL)),bionic stlport stlport_static),)
+my_test_libcxx := false
 endif
 endif
 
diff --git a/core/target_test_internal.mk b/core/target_test_internal.mk
index 50f4036..ed011d1 100644
--- a/core/target_test_internal.mk
+++ b/core/target_test_internal.mk
@@ -6,13 +6,12 @@
 
 LOCAL_C_INCLUDES += external/gtest/include
 
-my_test_libcxx := false
-ifndef LOCAL_SDK_VERSION
-ifeq (,$(TARGET_BUILD_APPS))
-ifneq ($(filter $(strip $(LOCAL_CXX_STL)),libc++ libc++_static),)
 my_test_libcxx := true
+ifdef LOCAL_SDK_VERSION
+my_test_libcxx := false
 endif
-endif
+ifneq ($(filter $(strip $(LOCAL_CXX_STL)),stlport stlport_static),)
+my_test_libcxx := false
 endif
 
 ifeq ($(my_test_libcxx),true)