diff --git a/darwin/main.m b/darwin/main.m
index cc78c938..db44cb60 100644
--- a/darwin/main.m
+++ b/darwin/main.m
@@ -99,12 +99,41 @@ void uiQueueMain(void (*f)(void *data), void *data)
 	dispatch_async_f(dispatch_get_main_queue(), data, f);
 }
 
+// Debugger() was deprecated in macOS 10.8 (as part of the larger CarbonCore deprecation), but they did not provide a replacement.
+// Though some people say inline asm, I'd rather make this work automatically everywhere.
+// Others say raise(SIGTRAP) and others still say __builtin_trap(), but I can't confirm these do what I want (some sources, including documentation, claim they either cause a core dump or send a SIGILL instead).
+// I've also heard of some new clang intrinsics, __builtin_debugtrap(), but this is totally undocumented and the original patch for this suggested it would be identical to __builtin_trap(), so...
+// Also I cannot figure out how to manually raise EXC_BREAKPOINT.
+// So that leaves us with one option: just use Debugger(), turning off the deprecation warnings.
+// Also, while we could turn off the deprecation warning temporarily in gcc >= 4.6 and any clang, I'm not sure what minimum version of gcc we need, and I'm not sure if "any clang" is even accurate.
+// So instead of juggling version macros, just turn off deprecation warnings at the bottom of this file.
+// References:
+// - https://stackoverflow.com/questions/37299/xcode-equivalent-of-asm-int-3-debugbreak-halt
+// - https://stackoverflow.com/questions/2622017/suppressing-deprecated-warnings-in-xcode
+// - https://stackoverflow.com/questions/28166565/detect-gcc-as-opposed-to-msvc-clang-with-macro
+// - https://stackoverflow.com/questions/16555585/why-pragma-gcc-diagnostic-push-pop-warning-in-gcc-c
+// - possibly others, all on stackoverflow.com (and maybe once on Apple's own forums?); I forget now
+static void debugBreak(void);
+
 void uiprivSysProgrammerError(const char *msg)
 {
 	NSLog(@"*** %s: %s. %s", uiprivProgrammerErrorPrefix, msg, uiprivProgrammerErrorAdvice);
 	// TODO either find an appropriate exception for each message or use a custom exception name
 	[NSException raise:NSInvalidArgumentException
 		format:@"%s: %s", uiprivProgrammerErrorPrefix, msg];
-	// TODO break into the debugger?
+	debugBreak();
 	abort();		// we shouldn't reach here
 }
+
+#ifdef __clang__
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
+#else
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+#endif
+static void debugBreak(void)
+{
+	Debugger();
+}
+
+// DO NOT ADD NEW CODE HERE. IT WILL NOT BE SUBJECT TO DEPRECATION WARNINGS.
+// I am making an exception here with Debugger(); see the large comment above.