--- a/js/src/builtin/TestingFunctions.cpp
+++ b/js/src/builtin/TestingFunctions.cpp
@@ -898,16 +898,22 @@ DumpHeapComplete(JSContext *cx, unsigned
 
     JS_SET_RVAL(cx, vp, JSVAL_VOID);
     return true;
 }
 
 static bool
 Terminate(JSContext *cx, unsigned arg, jsval *vp)
 {
+#ifdef JS_MORE_DETERMINISTIC
+    // Print a message to stderr in more-deterministic builds to help jsfunfuzz
+    // find uncatchable-exception bugs.
+    fprintf(stderr, "terminate called\n");
+#endif
+
     JS_ClearPendingException(cx);
     return false;
 }
 
 static bool
 EnableSPSProfilingAssertions(JSContext *cx, unsigned argc, jsval *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);

--- a/js/src/shell/js.cpp
+++ b/js/src/shell/js.cpp
@@ -1346,16 +1346,22 @@ PrintErr(JSContext *cx, unsigned argc, j
 }
 
 static bool
 Help(JSContext *cx, unsigned argc, jsval *vp);
 
 static bool
 Quit(JSContext *cx, unsigned argc, jsval *vp)
 {
+#ifdef JS_MORE_DETERMINISTIC
+    // Print a message to stderr in more-deterministic builds to help jsfunfuzz
+    // find uncatchable-exception bugs.
+    fprintf(stderr, "quit called\n");
+#endif
+
     CallArgs args = CallArgsFromVp(argc, vp);
     JS_ConvertArguments(cx, args.length(), args.array(), "/ i", &gExitCode);
 
     gQuitting = true;
     return false;
 }
 
 static const char *