diff --git a/tools/donate_cpu_lib.py b/tools/donate_cpu_lib.py
index cb6fe0790..daddaddf3 100644
--- a/tools/donate_cpu_lib.py
+++ b/tools/donate_cpu_lib.py
@@ -606,6 +606,25 @@ def diff_results(ver1, results1, ver2, results2):
         ret += ver2 + ' ' + r2[i2] + '\n'
         i2 += 1
 
+    # if there are syntaxError/unknownMacro/etc then analysis stops.
+    # diffing normal checker warnings will not make much sense
+    bailout_ids = ('[syntaxError]', '[unknownMacro]')
+    has_bailout_id = False
+    for id in bailout_ids:
+        if (id in results1) or (id in results1):
+            has_bailout_id = True
+    if has_bailout_id:
+        def check_bailout(line):
+            for id in bailout_ids:
+                if line.endswith(id):
+                    return True
+            return False
+        out = ''
+        for line in ret.split('\n'):
+            if check_bailout(line):
+                out += line + '\n'
+        ret = out
+
     return ret