diff --git a/.travis.yml b/.travis.yml
index 443960b..341c502 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -42,9 +42,14 @@
     - BUILD_LIBS="CPP C_GLIB HASKELL JAVA PYTHON TESTING TUTORIALS"  # only meaningful for CMake builds
 
   matrix:
-    - TEST_NAME="Cross Language Tests (Binary, Header, JSON Protocols)"
+    - TEST_NAME="Cross Language Tests (Binary Protocol)"
       SCRIPT="cross-test.sh"
-      BUILD_ARG="-'(binary|header|json)'"
+      BUILD_ARG="-'(binary)'"
+      BUILD_ENV="-e CC=clang -e CXX=clang++ -e THRIFT_CROSSTEST_CONCURRENCY=4"
+
+    - TEST_NAME="Cross Language Tests (Header, JSON Protocols)"
+      SCRIPT="cross-test.sh"
+      BUILD_ARG="-'(header|json)'"
       BUILD_ENV="-e CC=clang -e CXX=clang++ -e THRIFT_CROSSTEST_CONCURRENCY=4"
 
     - TEST_NAME="Cross Language Tests (Compact and Multiplexed Protocols)"
@@ -58,12 +63,12 @@
       DISTRO=centos-7.3
       SCRIPT="autotools.sh"
       BUILD_ENV="-e CC=gcc -e CXX=g++"
-      BUILD_ARG="--without-cpp --without-csharp --without-c_glib --without-d -without-dart --without-erlang --without-go --without-haskell --without-haxe"
+      BUILD_ARG="--without-cpp --without-csharp --without-c_glib --without-d -without-dart --without-erlang --without-go --without-haskell --without-haxe --without-nodejs"
 
     - TEST_NAME="Autotools (Ubuntu Xenial)"
       SCRIPT="autotools.sh"
       BUILD_ENV="-e CC=gcc -e CXX=g++"
-      BUILD_ARG="--enable-plugin --without-java --without-lua --without-nodejs --without-perl --without-php --without-php_extension --without-python --without-py3 --without-ruby --without-rust"
+      BUILD_ARG="--enable-plugin --without-java --without-lua --without-perl --without-php --without-php_extension --without-python --without-py3 --without-ruby --without-rust"
 
     # CMake builds
     - TEST_NAME="CMake (CentOS 7.3)"
@@ -89,11 +94,15 @@
 
     # C and C++ undefined behavior. This wraps autotools.sh, but each binary crashes if
     # undefined behavior occurs. Skips the known flaky tests.
+    # Unstable: THRIFT-4064 needs to be fixed perhaps
     - TEST_NAME="UBSan"
       SCRIPT="ubsan.sh"
-      BUILD_ARG="--without-haskell --without-nodejs --without-perl --without-python"
+      BUILD_ARG="--without-haskell --without-js --without-nodejs --without-perl --without-python"
+      UNSTABLE=true
 
 matrix:
+  allow_failures:
+    - env: UNSTABLE=true
   include:
     # QA jobs for code analytics and metrics
     #
diff --git a/build/docker/ubuntu-xenial/Dockerfile b/build/docker/ubuntu-xenial/Dockerfile
index 6324ec2..61ba5ff 100644
--- a/build/docker/ubuntu-xenial/Dockerfile
+++ b/build/docker/ubuntu-xenial/Dockerfile
@@ -141,7 +141,8 @@
       neko-dev \
       libneko0
 RUN haxelib setup --always /usr/share/haxe/lib && \
-    haxelib install --always hxcpp
+    haxelib install --always hxcpp 3.4.64
+# note: hxcpp 3.4.185 (latest) no longer ships static libraries, and caused a build failure
 
 RUN apt-get install -y --no-install-recommends \
 `# Java dependencies` \
diff --git a/lib/hs/thrift.cabal b/lib/hs/thrift.cabal
index f919127..fb33d9a 100644
--- a/lib/hs/thrift.cabal
+++ b/lib/hs/thrift.cabal
@@ -40,7 +40,7 @@
   Hs-Source-Dirs:
     src
   Build-Depends:
-    base >= 4, base < 5, containers, ghc-prim, attoparsec, binary, bytestring >= 0.10, base64-bytestring, hashable, HTTP, text, hspec-core < 2.4.0, unordered-containers >= 0.2.6, vector >= 0.10.12.2, QuickCheck >= 2.8.2, split
+    base >= 4, base < 5, containers, ghc-prim, attoparsec, binary, bytestring >= 0.10, base64-bytestring, hashable, HTTP, text, hspec-core > 2.4.0, unordered-containers >= 0.2.6, vector >= 0.10.12.2, QuickCheck >= 2.8.2, split
   if flag(network-uri)
      build-depends: network-uri >= 2.6, network >= 2.6
   else
diff --git a/test/known_failures_Linux.json b/test/known_failures_Linux.json
index efa0f56..0a5953a 100644
--- a/test/known_failures_Linux.json
+++ b/test/known_failures_Linux.json
@@ -2,22 +2,15 @@
   "cpp-cpp_binary_buffered-ip-ssl",
   "cpp-cpp_binary_framed-ip-ssl",
   "cpp-cpp_binary_http-domain",
-  "cpp-cpp_binary_http-ip",
   "cpp-cpp_binary_http-ip-ssl",
   "cpp-cpp_compact_buffered-ip-ssl",
   "cpp-cpp_compact_framed-ip-ssl",
-  "cpp-cpp_compact_http-domain",
-  "cpp-cpp_compact_http-ip",
   "cpp-cpp_compact_http-ip-ssl",
   "cpp-cpp_header_buffered-ip-ssl",
   "cpp-cpp_header_framed-ip-ssl",
-  "cpp-cpp_header_http-domain",
   "cpp-cpp_header_http-ip-ssl",
   "cpp-cpp_json_buffered-ip-ssl",
-  "cpp-cpp_json_framed-ip",
   "cpp-cpp_json_framed-ip-ssl",
-  "cpp-cpp_json_http-domain",
-  "cpp-cpp_json_http-ip",
   "cpp-cpp_json_http-ip-ssl",
   "cpp-dart_binary_http-ip",
   "cpp-dart_compact_http-ip",
@@ -34,60 +27,16 @@
   "cpp-java_compact_http-ip-ssl",
   "cpp-java_json_http-ip",
   "cpp-java_json_http-ip-ssl",
-  "csharp-c_glib_binary_buffered-ip-ssl",
-  "csharp-c_glib_binary_framed-ip-ssl",
-  "csharp-c_glib_compact_buffered-ip-ssl",
-  "csharp-c_glib_compact_framed-ip-ssl",
-  "csharp-cpp_binary_buffered-ip-ssl",
-  "csharp-cpp_binary_framed-ip-ssl",
-  "csharp-cpp_compact_buffered-ip-ssl",
-  "csharp-cpp_compact_framed-ip-ssl",
-  "csharp-cpp_json_buffered-ip-ssl",
-  "csharp-cpp_json_framed-ip-ssl",
   "csharp-d_binary_buffered-ip-ssl",
-  "csharp-d_compact_buffered-ip-ssl",
-  "csharp-d_json_buffered-ip-ssl",
   "csharp-d_binary_framed-ip-ssl",
+  "csharp-d_compact_buffered-ip-ssl",
   "csharp-d_compact_framed-ip-ssl",
+  "csharp-d_json_buffered-ip-ssl",
   "csharp-d_json_framed-ip-ssl",
   "csharp-erl_binary_buffered-ip-ssl",
   "csharp-erl_binary_framed-ip-ssl",
   "csharp-erl_compact_buffered-ip-ssl",
   "csharp-erl_compact_framed-ip-ssl",
-  "csharp-go_binary_buffered-ip-ssl",
-  "csharp-go_binary_framed-ip-ssl",
-  "csharp-go_compact_buffered-ip-ssl",
-  "csharp-go_compact_framed-ip-ssl",
-  "csharp-go_json_buffered-ip-ssl",
-  "csharp-go_json_framed-ip-ssl",
-  "csharp-nodejs_binary_buffered-ip-ssl",
-  "csharp-nodejs_binary_framed-ip-ssl",
-  "csharp-nodejs_compact_buffered-ip-ssl",
-  "csharp-nodejs_compact_framed-ip-ssl",
-  "csharp-nodejs_json_buffered-ip-ssl",
-  "csharp-nodejs_json_framed-ip-ssl",
-  "csharp-perl_binary_buffered-ip-ssl",
-  "csharp-perl_binary_framed-ip-ssl",
-  "csharp-py3_binary-accel_buffered-ip-ssl",
-  "csharp-py3_binary-accel_framed-ip-ssl",
-  "csharp-py3_binary_buffered-ip-ssl",
-  "csharp-py3_binary_framed-ip-ssl",
-  "csharp-py3_compact-accelc_buffered-ip-ssl",
-  "csharp-py3_compact-accelc_framed-ip-ssl",
-  "csharp-py3_compact_buffered-ip-ssl",
-  "csharp-py3_compact_framed-ip-ssl",
-  "csharp-py3_json_buffered-ip-ssl",
-  "csharp-py3_json_framed-ip-ssl",
-  "csharp-py_binary-accel_buffered-ip-ssl",
-  "csharp-py_binary-accel_framed-ip-ssl",
-  "csharp-py_binary_buffered-ip-ssl",
-  "csharp-py_binary_framed-ip-ssl",
-  "csharp-py_compact-accelc_buffered-ip-ssl",
-  "csharp-py_compact-accelc_framed-ip-ssl",
-  "csharp-py_compact_buffered-ip-ssl",
-  "csharp-py_compact_framed-ip-ssl",
-  "csharp-py_json_buffered-ip-ssl",
-  "csharp-py_json_framed-ip-ssl",
   "d-cpp_binary_buffered-ip",
   "d-cpp_binary_buffered-ip-ssl",
   "d-cpp_binary_framed-ip",
@@ -202,10 +151,8 @@
   "go-d_compact_http-ip-ssl",
   "go-d_json_http-ip",
   "go-d_json_http-ip-ssl",
-  "go-dart_binary_framed-ip",
   "go-dart_binary_http-ip",
   "go-dart_compact_http-ip",
-  "go-dart_json_framed-ip",
   "go-dart_json_http-ip",
   "go-java_binary_http-ip",
   "go-java_binary_http-ip-ssl",
@@ -214,17 +161,12 @@
   "go-java_json_http-ip",
   "go-java_json_http-ip-ssl",
   "go-nodejs_json_framed-ip",
-  "hs-csharp_binary_framed-ip",
-  "hs-csharp_compact_framed-ip",
-  "hs-csharp_json_framed-ip",
   "hs-dart_binary_framed-ip",
   "hs-dart_compact_framed-ip",
   "hs-dart_json_framed-ip",
-  "hs-py3_json_buffered-ip",
-  "hs-py3_json_framed-ip",
   "java-d_compact_buffered-ip",
   "java-d_compact_buffered-ip-ssl",
   "java-d_compact_framed-ip",
   "rs-dart_binary_framed-ip",
   "rs-dart_compact_framed-ip"
-]
+]
\ No newline at end of file