diff --git a/common/errors.c b/common/errors.c
index 82ba26c6..c7a8448d 100644
--- a/common/errors.c
+++ b/common/errors.c
@@ -26,13 +26,13 @@ void uiprivInternalError(const char *fmt, ...)
 // TODO add debugging advice?
 #define programmerErrorSuffix "This likely means you are using libui incorrectly. Check your source code and try again. If you have received this warning in error, contact the libui authors."
 
-static uiprivTestHookReportProgrammerErrorFunc reportProgrammerErrorTestHook = uiprivReportError;
+static uiprivTestHookReportProgrammerErrorFunc reportProgrammerErrorTestHook = NULL;
+static void *reportProgrammerErrorTestHookData = NULL;
 
-void uiprivTestHookReportProgrammerError(uiprivTestHookReportProgrammerErrorFunc f)
+void uiprivTestHookReportProgrammerError(uiprivTestHookReportProgrammerErrorFunc f, void *data)
 {
-	if (f == NULL)
-		f = uiprivReportError;
 	reportProgrammerErrorTestHook = f;
+	reportProgrammerErrorTestHookData = data;
 }
 
 void uiprivProgrammerError(const char *fmt, ...)
@@ -48,5 +48,9 @@ void uiprivProgrammerError(const char *fmt, ...)
 	if (n >= 256)
 		uiprivInternalError("programmer error string too long (%d)", n);
 	va_end(ap);
-	(*reportProgrammerErrorTestHook)(programmerErrorPrefix, buf, programmerErrorSuffix, false);
+	if (reportProgrammerErrorTestHook != NULL) {
+		(*reportProgrammerErrorTestHook)(buf, reportProgrammerErrorTestHookData);
+		return;
+	}
+	uiprivReportError(programmerErrorPrefix, buf, programmerErrorSuffix, false);
 }
diff --git a/common/testhooks.h b/common/testhooks.h
index b1d9ce3d..986c6fc4 100644
--- a/common/testhooks.h
+++ b/common/testhooks.h
@@ -5,8 +5,8 @@ extern "C" {
 #endif
 
 // errors.c
-typedef void (*uiprivTestHookReportProgrammerErrorFunc)(const char *prefix, const char *msg, const char *suffix, bool internal);
-uiprivExtern void uiprivTestHookReportProgrammerError(uiprivTestHookReportProgrammerErrorFunc f);
+typedef void (*uiprivTestHookReportProgrammerErrorFunc)(const char *msg, void *data);
+uiprivExtern void uiprivTestHookReportProgrammerError(uiprivTestHookReportProgrammerErrorFunc f, void *data);
 
 #ifdef __cplusplus
 }