diff --git a/CMake/VTKmMacros.cmake b/CMake/VTKmMacros.cmake
index 7b5c2e091..999010b00 100644
--- a/CMake/VTKmMacros.cmake
+++ b/CMake/VTKmMacros.cmake
@@ -220,7 +220,7 @@ function(vtkm_unit_tests)
 
   if(VTKm_ENABLE_OPENGL_INTEROP)
     list(APPEND VTKm_UT_INCLUDE_DIRS ${OPENGL_INCLUDE_DIR} ${GLEW_INCLUDE_DIR} )
-    list(APPEND VTKm_UT_LIBRARIES ${OPENGL_LIBRARIES} ${GLEW_LIBRARIES} )
+    list(APPEND VTKm_UT_LIBRARIES ${OPENGL_LIBRARIES} ${GLEW_LIBRARIES} ${CMAKE_THREAD_LIBS_INIT} )
   endif()
 
   if(VTKm_ENABLE_OPENGL_TESTS)
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4bad4198c..1f819e410 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -165,6 +165,12 @@ CMAKE_DEPENDENT_OPTION(VTKm_ENABLE_OPENGL_TESTS
                        "Enable OpenGL Interop Render Window Tests"
                        ON "VTKm_ENABLE_OPENGL_INTEROP;GLUT_FOUND" OFF)
 
+#on unix/linux Glew uses pthreads, so we need to find that, and link to it
+#explicitly or else in release mode we get sigsegv on launch
+if(UNIX AND VTKm_ENABLE_OPENGL_INTEROP)
+  find_package(Threads REQUIRED)
+endif()
+
 #-----------------------------------------------------------------------------
 # Find Pyexpander in case somebody wants to update the auto generated
 # faux variadic template code