diff --git a/.ccls b/.ccls
index ab6261583..d79e21d79 100644
--- a/.ccls
+++ b/.ccls
@@ -17,6 +17,8 @@
 -I./python/pybind11/include/
 -I./external/Vulkan-Headers/include/
 -I./external/googletest/googletest/include/
+-I./external/shaderc/libshaderc/include/
+-I./external/shaderc/libshaderc_util/include/
 -I./external/spdlog/include/
 -I./src/include/
 -I./single_include/
diff --git a/.gitmodules b/.gitmodules
index 7b7ada44f..086a6f8fd 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -14,3 +14,7 @@
 	path = python/pybind11
 	url = https://github.com/pybind/pybind11
     branch = v2.6.1
+[submodule "external/shaderc"]
+	path = external/shaderc
+	url = https://github.com/google/shaderc
+    branch = v2020.4
diff --git a/Makefile b/Makefile
index f77970759..c2b667fd4 100644
--- a/Makefile
+++ b/Makefile
@@ -70,6 +70,7 @@ mk_cmake:
 		-DKOMPUTE_OPT_ENABLE_SPDLOG=1 \
 		-DSPDLOG_INSTALL=1 \
 		-DKOMPUTE_OPT_CODE_COVERAGE=1 \
+		-DSHADERC_SKIP_TESTS=1 \
 		-G "Unix Makefiles"
 
 mk_build_all:
@@ -88,7 +89,7 @@ mk_run_docs: mk_build_docs
 	(cd build/docs/sphinx && python2.7 -m SimpleHTTPServer)
 
 mk_run_tests: mk_build_tests
-	./build/test/test_kompute $(FILTER_TESTS)
+	./build/test/test_kompute --gtest_filter=$(FILTER_TESTS)
 
 mk_build_swiftshader_library:
 	git clone https://github.com/google/swiftshader || echo "Assuming already cloned"
@@ -99,6 +100,9 @@ mk_build_swiftshader_library:
 mk_run_tests_cpu: export VK_ICD_FILENAMES=$(PWD)/swiftshader/build/vk_swiftshader_icd.json
 mk_run_tests_cpu: mk_build_swiftshader_library mk_build_tests mk_run_tests_cpu_only
 
+mk_run_tests_only:
+	./build/test/test_kompute --gtest_filter="-TestAsyncOperations.*"
+
 mk_run_tests_cpu_only:
 	./build/test/test_kompute --gtest_filter="TestLogisticRegressionAlgorithm.*"
 	./build/test/test_kompute --gtest_filter="TestManager.*"
@@ -133,6 +137,7 @@ vs_cmake:
 		-DKOMPUTE_OPT_BUILD_SINGLE_HEADER=1 \
 		-DKOMPUTE_OPT_ENABLE_SPDLOG=1 \
 		-DSPDLOG_INSTALL=1 \
+		-DSHADERC_SKIP_TESTS=1 \
 		-G "Visual Studio 16 2019"
 
 vs_build_all:
diff --git a/external/shaderc b/external/shaderc
new file mode 160000
index 000000000..0dbd89994
--- /dev/null
+++ b/external/shaderc
@@ -0,0 +1 @@
+Subproject commit 0dbd899941a43ffd55df527d65128b3b66e75c9c
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index b38f7bdae..77d0d1c4b 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -1,4 +1,7 @@
 
+#####################################################
+#################### GETEST #######################
+#####################################################
 enable_testing()
 if(KOMPUTE_OPT_REPO_SUBMODULE_BUILD)
     add_subdirectory(${PROJECT_SOURCE_DIR}/external/googletest EXCLUDE_FROM_ALL
@@ -35,6 +38,35 @@ target_link_libraries(test_kompute PRIVATE kompute)
 
 add_test(NAME test_kompute COMMAND test_kompute)
 
+#####################################################
+#################### PYSHADERC #######################
+#####################################################
+
+if(KOMPUTE_OPT_REPO_SUBMODULE_BUILD)
+    add_subdirectory(${PROJECT_SOURCE_DIR}/external/shaderc EXCLUDE_FROM_ALL
+        ${CMAKE_CURRENT_BINARY_DIR}/kompute_shaderc)
+
+    target_include_directories(
+        test_kompute PRIVATE
+        ${shaderc_SOURCE_DIR}/include)
+
+    target_link_libraries(test_kompute PRIVATE
+        shaderc_combined)
+else()
+    find_library(SHADERC_LIB shaderc_combined)
+
+    find_path(SHADERC_INCLUDE_DIRS shaderc)
+
+    target_include_directories(
+        test_kompute PRIVATE
+        ${SHADERC_INCLUDE_DIRS}/include)
+
+    MESSAGE(STATUS "INclude dirs:" ${SHADERC_INCLUDE_DIRS})
+
+    target_link_libraries(test_kompute PRIVATE
+        shaderc_combined)
+endif()
+
 #####################################################
 #################### CODECOV  #######################
 #####################################################
diff --git a/test/TestSpecializationConstant.cpp b/test/TestSpecializationConstant.cpp
new file mode 100644
index 000000000..05fb19420
--- /dev/null
+++ b/test/TestSpecializationConstant.cpp
@@ -0,0 +1,51 @@
+
+#include "gtest/gtest.h"
+
+#include "kompute/Kompute.hpp"
+
+
+TEST(TestSpecializationConstants, TestTwoConstants)
+{
+    std::shared_ptr<kp::Tensor> tensorA{ new kp::Tensor({ 0, 0, 0 }) };
+    std::shared_ptr<kp::Tensor> tensorB{ new kp::Tensor({ 0, 0, 0 }) };
+
+    std::string shader(R"(
+      #version 450
+      layout (constant_id = 0) const float cOne = 1;
+      layout (constant_id = 1) const float cTwo = 1;
+      layout (local_size_x = 1) in;
+      layout(set = 0, binding = 0) buffer a { float pa[]; };
+      layout(set = 0, binding = 1) buffer b { float pb[]; };
+      void main() {
+          uint index = gl_GlobalInvocationID.x;
+          pa[index] = cOne;
+          pb[index] = cTwo;
+      })");
+
+    {
+        std::shared_ptr<kp::Sequence> sq = nullptr;
+
+        {
+            kp::Manager mgr;
+
+            mgr.rebuild({ tensorA, tensorB });
+
+            sq = mgr.sequence();
+
+            auto spec = kp::Constants({5.0, 0.3});
+
+            sq->begin();
+            sq->record<kp::OpAlgoBase>(
+              { tensorA, tensorB },
+              std::vector<char>(shader.begin(), shader.end()),
+              kp::Workgroup(), spec);
+            sq->end();
+
+            sq->eval();
+
+            mgr.evalOpDefault<kp::OpTensorSyncLocal>({ tensorA, tensorB });
+        }
+    }
+    EXPECT_EQ(tensorA->data(), std::vector<float>({ 5, 5, 5 }));
+    EXPECT_EQ(tensorB->data(), std::vector<float>({ 0.3, 0.3, 0.3 }));
+}
diff --git a/test/TestUtils.cpp b/test/TestUtils.cpp
new file mode 100644
index 000000000..59444f5f8
--- /dev/null
+++ b/test/TestUtils.cpp
@@ -0,0 +1,27 @@
+
+#include <iostream>
+#include <vector>
+
+#include <shaderc/shaderc.hpp>
+
+static std::vector<uint32_t> spirv_from_string(const std::string& source,
+                                   shaderc_optimization_level optimization = shaderc_optimization_level_size,
+                                   std::vector<std::pair<std::string,std::string>> definitions = {}) {
+  shaderc::Compiler compiler;
+  shaderc::CompileOptions options;
+
+  for (const std::pair<std::string,std::string>& def : definitions) {
+      options.AddMacroDefinition(def.first, def.second);
+  }
+  if (optimization) options.SetOptimizationLevel(optimization);
+
+  std::string errorTag = "kompute";
+  shaderc::SpvCompilationResult module =
+      compiler.CompileGlslToSpv(source, shaderc_glsl_default_compute_shader, errorTag.c_str(), options);
+
+  if (module.GetCompilationStatus() != shaderc_compilation_status_success)  {
+    throw std::runtime_error("Shader string invalid: " + module.GetErrorMessage());
+  }
+
+  return {module.cbegin(), module.cend()};
+}