diff --git a/test/events.c b/test/events.c
index eefad3ed..940bcedc 100644
--- a/test/events.c
+++ b/test/events.c
@@ -94,11 +94,11 @@ static void runFull(testingT *t, const char *file, long line, uiEvent *e, void *
 		if (h->gotRun && h->wantRun) {
 			// only check these if it was correctly run, to reduce noise if the above failed
 			if (h->gotSender != h->wantSender)
-				diff_2str(t, "incorrect sender seen by", h->name,
-					"%p", h->gotSender, h->wantSender);
+				testingTErrorfFull(t, file, line, "incorrect sender seen by %s:" diffx("%p"),
+					h->name, h->gotSender, h->wantSender);
 			if (h->gotArgs != h->wantArgs)
-				diff_2str(t, "incorrect args seen by", h->name,
-					"%p", h->gotArgs, h->wantArgs);
+				testingTErrorfFull(t, file, line, "incorrect args seen by %s:" diffx("%p"),
+					h->name, h->gotArgs, h->wantArgs);
 		}
 		if (h->validID) {
 			// the following call will fail if the ID isn't valid
@@ -111,8 +111,8 @@ static void runFull(testingT *t, const char *file, long line, uiEvent *e, void *
 		h++;
 	}
 	if (gotRunCount != wantRunCount)
-		diff(t, "incorrect number of handler runs",
-			"%d", gotRunCount, wantRunCount);
+		testingTErrorfFull(t, file, line, "incorrect number of handler runs:" diffx("%d"),
+			gotRunCount, wantRunCount);
 }
 
 #define run(t, e, sender, args, handlers, n, wantRunCount) runFull(t, __FILE__, __LINE__, e, sender, args, handlers, n, wantRunCount)
diff --git a/test/initmain.c b/test/initmain.c
index c15bc7f7..5db32a04 100644
--- a/test/initmain.c
+++ b/test/initmain.c
@@ -24,7 +24,7 @@ testingTestInSet(beforeTests, Init)
 	if (uiInit(&err, &err))
 		testingTErrorf(t, "uiInit() with non-NULL options succeeded; expected failure");
 	if (strcmp(err.Message, errInvalidOptions) != 0)
-		diff(t, "uiInit() with non-NULL options returned bad error message", "%s",
+		testingTErrorf(t, "uiInit() with non-NULL options returned bad error message:" diffx("%s"),
 			err.Message, errInvalidOptions);
 }
 
@@ -37,7 +37,7 @@ testingTest(InitAfterInitialized)
 	if (uiInit(NULL, &err))
 		testingTErrorf(t, "uiInit() after a previous successful call succeeded; expected failure");
 	if (strcmp(err.Message, errAlreadyInitialized) != 0)
-		diff(t, "uiInit() after a previous successful call returned bad error message", "%s",
+		testingTErrorf(t, "uiInit() after a previous successful call returned bad error message:" diffx("%s"),
 			err.Message, errAlreadyInitialized);
 }
 
@@ -69,7 +69,7 @@ testingTest(QueueMain)
 	uiQueueMain(queued, &p);
 	timeout_uiMain(t, 5 * timerSecond);
 	if (p.flag != 1)
-		diff(t, "uiQueueMain() didn't set flag properly", "%d",
+		testingTErrorf(t, "uiQueueMain() didn't set flag properly:" diffx("%d"),
 			p.flag, 1);
 }
 
@@ -165,7 +165,7 @@ testingTest(QueueMain_DifferentThread)
 	if (p.err != 0)
 		testingTErrorf(t, "error sleeping in thread to ensure a high likelihood the uiQueueMain() is run after uiMain() starts: " timerSysErrorFmt, timerSysErrorFmtArg(p.err));
 	if (p.flag != 1)
-		diff(t, "uiQueueMain() didn't set flag properly", "%d",
+		testingTErrorf(t, "uiQueueMain() didn't set flag properly:" diffx("%d"),
 			p.flag, 1);
 }
 
diff --git a/test/main.c b/test/main.c
index 53a08a41..68b432c9 100644
--- a/test/main.c
+++ b/test/main.c
@@ -16,8 +16,8 @@ void catchProgrammerError(const char *prefix, const char *msg, const char *suffi
 	if (internal)
 		testingTErrorfFull(errorParams.t, errorParams.file, errorParams.line, "%s error is marked internal; should not have been", errorParams.exprstr);
 	if (strstr(msg, errorParams.msgWant) == NULL)
-		diff_2str(errorParams.t, errorParams.exprstr, "message doesn't contain expected substring",
-			"%s", msg, errorParams.msgWant);
+		testingTErrorf(errorParams.t, errorParams.file, errorParams.line, "%s: message doesn't contain expected substring:" diffx("%s"),
+			errorParams.exprstr, msg, errorParams.msgWant);
 }
 
 static void runSetORingResults(testingSet *set, const struct testingOptions *options, bool *anyRun, bool *anyFailed)
diff --git a/test/noinitwrongthread.c b/test/noinitwrongthread.c
index f4a77d9d..30d5d7df 100644
--- a/test/noinitwrongthread.c
+++ b/test/noinitwrongthread.c
@@ -125,8 +125,8 @@ static void reportCases(testingT *t, struct errorCase *p)
 		if (p->internalGot)
 			testingTErrorfFull(t, p->file, p->line, "%s error is marked internal; should not have been", p->name);
 		if (p->msgGot != NULL)
-			diff_2str(t, p->name, "message doesn't contain expected substring",
-				"%s", p->msgGot, p->msgWant);
+			testingTErrorfFull(t, p->file, p->line, "%s message doesn't contain expected substring:" diffx("%s"),
+				p->name, p->msgGot, p->msgWant);
 		p = p->next;
 	}
 }
diff --git a/test/test.h b/test/test.h
index 35e722ae..9ba03cb1 100644
--- a/test/test.h
+++ b/test/test.h
@@ -11,8 +11,6 @@
 #include "lib/timer.h"
 
 #define diffx(fmt) "\ngot  " fmt "\nwant " fmt
-#define diff(t, clause, fmt, got, want) testingTErrorf(t, "%s:\ngot  " fmt "\nwant " fmt, clause, got, want)
-#define diff_2str(t, clause, clause2, fmt, got, want) testingTErrorf(t, "%s %s:\ngot  " fmt "\nwant " fmt, clause, clause2, got, want)
 
 // main.c
 extern void timeoutMain(void *data);
@@ -32,7 +30,6 @@ struct errorParams {
 	testingT *t;
 	const char *file;
 	long line;
-	// TODO this shouldn't have a colon in it but the diff() macros above necessitate it
 	const char *exprstr;
 	const char *msgWant;
 	bool caught;
@@ -45,7 +42,7 @@ extern void catchProgrammerError(const char *prefix, const char *msg, const char
 	errorParams.t = tt; \
 	errorParams.file = __FILE__; \
 	errorParams.line = __LINE__; \
-	errorParams.exprstr = #expr ":"; \
+	errorParams.exprstr = #expr; \
 	errorParams.msgWant = mw; \
 	errorParams.caught = false; \
 	expr; \