diff --git a/plugins/SedRegex/plugin.py b/plugins/SedRegex/plugin.py
index 233429b17..f0fd7228f 100644
--- a/plugins/SedRegex/plugin.py
+++ b/plugins/SedRegex/plugin.py
@@ -66,6 +66,7 @@ class SedRegex(callbacks.PluginRegexp):
     threaded = True
     public = True
     unaddressedRegexps = ['replacer']
+    flags = 0  # Make callback matching case sensitive
 
     @staticmethod
     def _unpack_sed(expr):
diff --git a/plugins/SedRegex/test.py b/plugins/SedRegex/test.py
index 50a045ca5..37736256a 100644
--- a/plugins/SedRegex/test.py
+++ b/plugins/SedRegex/test.py
@@ -57,6 +57,10 @@ class SedRegexTestCase(ChannelPluginTestCase):
         m = self.getMsg(' ')
         self.assertIn('eliens', str(m))
 
+    def testIgnoreRegexpWithBadCase(self):
+        self.feedMsg('aliens are invading, help!')
+        self.assertNoResponse('S/aliens/monsters/')
+
     def testGlobalReplace(self):
         self.feedMsg('AAaa aaAa a b')
         self.feedMsg('s/a/e/g')