diff --git a/third_party/pthreadpool/CMakeLists.txt b/third_party/pthreadpool/CMakeLists.txt
index 0db3264..1ba91c4 100644
--- a/third_party/pthreadpool/CMakeLists.txt
+++ b/third_party/pthreadpool/CMakeLists.txt
@@ -74,9 +74,7 @@ IF(EMSCRIPTEN)
   LIST(APPEND PTHREADPOOL_SRCS src/shim.c)
 ELSE()
   LIST(APPEND PTHREADPOOL_SRCS src/portable-api.c src/memory.c)
-  IF(APPLE AND (PTHREADPOOL_SYNC_PRIMITIVE STREQUAL "default" OR PTHREADPOOL_SYNC_PRIMITIVE STREQUAL "gcd"))
-    LIST(APPEND PTHREADPOOL_SRCS src/gcd.c)
-  ELSEIF(CMAKE_SYSTEM_NAME MATCHES "^(Windows|CYGWIN|MSYS)$" AND (PTHREADPOOL_SYNC_PRIMITIVE STREQUAL "default" OR PTHREADPOOL_SYNC_PRIMITIVE STREQUAL "event"))
+  IF(CMAKE_SYSTEM_NAME MATCHES "^(Windows|CYGWIN|MSYS)$" AND (PTHREADPOOL_SYNC_PRIMITIVE STREQUAL "default" OR PTHREADPOOL_SYNC_PRIMITIVE STREQUAL "event"))
     LIST(APPEND PTHREADPOOL_SRCS src/windows.c)
   ELSE()
     LIST(APPEND PTHREADPOOL_SRCS src/pthreads.c)
@@ -111,10 +109,6 @@ ELSEIF(PTHREADPOOL_SYNC_PRIMITIVE STREQUAL "futex")
   TARGET_COMPILE_DEFINITIONS(pthreadpool PRIVATE PTHREADPOOL_USE_FUTEX=1)
   TARGET_COMPILE_DEFINITIONS(pthreadpool PRIVATE PTHREADPOOL_USE_GCD=0)
   TARGET_COMPILE_DEFINITIONS(pthreadpool PRIVATE PTHREADPOOL_USE_EVENT=0)
-ELSEIF(PTHREADPOOL_SYNC_PRIMITIVE STREQUAL "gcd")
-  TARGET_COMPILE_DEFINITIONS(pthreadpool PRIVATE PTHREADPOOL_USE_FUTEX=0)
-  TARGET_COMPILE_DEFINITIONS(pthreadpool PRIVATE PTHREADPOOL_USE_GCD=1)
-  TARGET_COMPILE_DEFINITIONS(pthreadpool PRIVATE PTHREADPOOL_USE_EVENT=0)
 ELSEIF(PTHREADPOOL_SYNC_PRIMITIVE STREQUAL "event")
   TARGET_COMPILE_DEFINITIONS(pthreadpool PRIVATE PTHREADPOOL_USE_FUTEX=0)
   TARGET_COMPILE_DEFINITIONS(pthreadpool PRIVATE PTHREADPOOL_USE_GCD=0)
diff --git a/third_party/pthreadpool/src/threadpool-common.h b/third_party/pthreadpool/src/threadpool-common.h
index ca84744..244d0ca 100644
--- a/third_party/pthreadpool/src/threadpool-common.h
+++ b/third_party/pthreadpool/src/threadpool-common.h
@@ -14,14 +14,6 @@
 	#endif
 #endif
 
-#ifndef PTHREADPOOL_USE_GCD
-	#if defined(__APPLE__)
-		#define PTHREADPOOL_USE_GCD 1
-	#else
-		#define PTHREADPOOL_USE_GCD 0
-	#endif
-#endif
-
 #ifndef PTHREADPOOL_USE_EVENT
 	#if defined(_WIN32) || defined(__CYGWIN__)
 		#define PTHREADPOOL_USE_EVENT 1