diff --git a/test/noinitwrongthread.c b/test/noinitwrongthread.c
index 756254de..00476fd5 100644
--- a/test/noinitwrongthread.c
+++ b/test/noinitwrongthread.c
@@ -2,19 +2,8 @@
 #include "test.h"
 #include "thread.h"
 
-// TODO split the macros in this file into its own file
-
-// TODO rename to FunctionsFailBeforeInit?
-#define allcallsCase(f, ...) \
-	TestNoInit(CallBeforeInitIsProgrammerError_ ## f) \
-	{ \
-		void *ctx; \
-		ctx = beginCheckProgrammerError("attempt to call " #f "() before uiInit()"); \
-		f(__VA_ARGS__); \
-		endCheckProgrammerError(ctx); \
-	}
-#include "allcalls.h"
-#undef allcallsCase
+#define allcallsHeader "allcalls.h"
+#include "noinitwrongthreadimpl.h"
 
 TestNoInit(CallBeforeInitIsProgrammerError_uiQueueMain)
 {
@@ -25,27 +14,4 @@ TestNoInit(CallBeforeInitIsProgrammerError_uiQueueMain)
 	endCheckProgrammerError(ctx);
 }
 
-// TODO rename to FunctionsFailOnWrongThread?
-#define allcallsCase(f, ...) \
-	static void threadTest ## f(void *data) \
-	{ \
-		f(__VA_ARGS__); \
-	} \
-	Test(CallOnWrongThreadIsProgrammerError_ ## f) \
-	{ \
-		threadThread *thread; \
-		threadSysError err; \
-		void *ctx; \
-		ctx = beginCheckProgrammerError("attempt to call " #f "() on a thread other than the GUI thread"); \
-		err = threadNewThread(threadTest ## f, NULL, &thread); \
-		if (err != 0) \
-			TestFatalf("error creating thread: " threadSysErrorFmt, threadSysErrorFmtArg(err)); \
-		err = threadThreadWaitAndFree(thread); \
-		if (err != 0) \
-			TestFatalf("error waiting for thread to finish: " threadSysErrorFmt, threadSysErrorFmtArg(err)); \
-		endCheckProgrammerError(ctx); \
-	}
-#include "allcalls.h"
-#undef allcallsCase
-
 // no uiQueueMain() test for the wrong thread; it's supposed to be callable from any thread
diff --git a/test/noinitwrongthread_darwin.m b/test/noinitwrongthread_darwin.m
index 2b701a01..9cc36ede 100644
--- a/test/noinitwrongthread_darwin.m
+++ b/test/noinitwrongthread_darwin.m
@@ -2,37 +2,5 @@
 #import "test_darwin.h"
 #import "thread.h"
 
-// TODO rename to FunctionsFailBeforeInit?
-#define allcallsCase(f, ...) \
-	TestNoInit(CallBeforeInitIsProgrammerError_ ## f) \
-	{ \
-		void *ctx; \
-		ctx = beginCheckProgrammerError("attempt to call " #f "() before uiInit()"); \
-		f(__VA_ARGS__); \
-		endCheckProgrammerError(ctx); \
-	}
-#include "allcalls_darwin.h"
-#undef allcallsCase
-
-// TODO rename to FunctionsFailOnWrongThread?
-#define allcallsCase(f, ...) \
-	static void threadTest ## f(void *data) \
-	{ \
-		f(__VA_ARGS__); \
-	} \
-	Test(CallOnWrongThreadIsProgrammerError_ ## f) \
-	{ \
-		threadThread *thread; \
-		threadSysError err; \
-		void *ctx; \
-		ctx = beginCheckProgrammerError("attempt to call " #f "() on a thread other than the GUI thread"); \
-		err = threadNewThread(threadTest ## f, NULL, &thread); \
-		if (err != 0) \
-			TestFatalf("error creating thread: " threadSysErrorFmt, threadSysErrorFmtArg(err)); \
-		err = threadThreadWaitAndFree(thread); \
-		if (err != 0) \
-			TestFatalf("error waiting for thread to finish: " threadSysErrorFmt, threadSysErrorFmtArg(err)); \
-		endCheckProgrammerError(ctx); \
-	}
-#include "allcalls_darwin.h"
-#undef allcallsCase
+#define allcallsHeader "allcalls_darwin.h"
+#include "noinitwrongthreadimpl.h"
diff --git a/test/noinitwrongthreadimpl.h b/test/noinitwrongthreadimpl.h
new file mode 100644
index 00000000..0d015edc
--- /dev/null
+++ b/test/noinitwrongthreadimpl.h
@@ -0,0 +1,37 @@
+// 28 may 2019
+// define allcallsHeader and include test.h and thread.h before including this
+
+// TODO rename to FunctionsFailBeforeInit?
+#define allcallsCase(f, ...) \
+	TestNoInit(CallBeforeInitIsProgrammerError_ ## f) \
+	{ \
+		void *ctx; \
+		ctx = beginCheckProgrammerError("attempt to call " #f "() before uiInit()"); \
+		f(__VA_ARGS__); \
+		endCheckProgrammerError(ctx); \
+	}
+#include allcallsHeader
+#undef allcallsCase
+
+// TODO rename to FunctionsFailOnWrongThread?
+#define allcallsCase(f, ...) \
+	static void threadTest ## f(void *data) \
+	{ \
+		f(__VA_ARGS__); \
+	} \
+	Test(CallOnWrongThreadIsProgrammerError_ ## f) \
+	{ \
+		threadThread *thread; \
+		threadSysError err; \
+		void *ctx; \
+		ctx = beginCheckProgrammerError("attempt to call " #f "() on a thread other than the GUI thread"); \
+		err = threadNewThread(threadTest ## f, NULL, &thread); \
+		if (err != 0) \
+			TestFatalf("error creating thread: " threadSysErrorFmt, threadSysErrorFmtArg(err)); \
+		err = threadThreadWaitAndFree(thread); \
+		if (err != 0) \
+			TestFatalf("error waiting for thread to finish: " threadSysErrorFmt, threadSysErrorFmtArg(err)); \
+		endCheckProgrammerError(ctx); \
+	}
+#include allcallsHeader
+#undef allcallsCase