diff --git a/CMakeLists.txt b/CMakeLists.txt
index 46f9a83de..289e72952 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -18,6 +18,7 @@ message(STATUS "C++ version ${CXX_STANDARD} configured.")
 
 option(XACC_BUILD_TESTS "Build test programs" OFF)
 option(XACC_BUILD_EXAMPLES "Build example programs" OFF)
+option(XACC_MULTI_THREADED "Enable multi-thread support" OFF)
 option(XACC_ENSMALLEN_INCLUDE_DIR "Path to ensmallen.hpp for mlpack optimizer" "")
 option(XACC_ARMADILLO_INCLUDE_DIR "Path to armadillo header for mlpack optimizer" "")
 
@@ -101,6 +102,13 @@ endif()
 
 message(STATUS "${BoldGreen}Installing XACC to ${CMAKE_INSTALL_PREFIX}. Override with -DCMAKE_INSTALL_PREFIX=...${ColorReset}")
 
+if (XACC_MULTI_THREADED)
+  message(STATUS "${BoldGreen}Multi-thread support is enabled ${ColorReset}")
+  add_compile_definitions(_XACC_MUTEX)
+else()
+  message(STATUS "${BoldGreen}Multi-thread support is disabled (default)${ColorReset}")
+endif()
+
 if (XACC_BUILD_TESTS)
    enable_testing()
    macro(add_xacc_test _TEST_NAME)
diff --git a/xacc/xacc.hpp b/xacc/xacc.hpp
index 88b480b8f..9953f6880 100644
--- a/xacc/xacc.hpp
+++ b/xacc/xacc.hpp
@@ -28,7 +28,6 @@
 #include <sys/stat.h>
 #include <fstream>
 
-#undef _XACC_MUTEX
 #ifdef _XACC_MUTEX
 #include <mutex>
 #endif