--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -13,6 +13,16 @@ cmake_policy(SET CMP0077 NEW)
 #  cmake_policy(SET CMP0028 NEW)
 #endif()
 
+# https://stackoverflow.com/questions/54587052/cmake-on-mac-could-not-find-threads-missing-threads-found
+# assume built-in pthreads on Unix
+IF(UNIX)
+    set(CMAKE_THREAD_LIBS_INIT "-lpthread")
+    set(CMAKE_HAVE_THREADS_LIBRARY 1)
+    set(CMAKE_USE_WIN32_THREADS_INIT 0)
+    set(CMAKE_USE_PTHREADS_INIT 1)
+    set(THREADS_PREFER_PTHREAD_FLAG ON)
+ENDIF()
+
 project(mamba)
 
 # Build options