diff --git a/linter.py b/linter.py
index 1393739..c6f8556 100644
--- a/linter.py
+++ b/linter.py
@@ -11,21 +11,23 @@
 """This module exports the PHP plugin class."""
 
 import logging
+import re
 from SublimeLinter.lint import Linter, util
 
 
 logger = logging.getLogger('SublimeLinter.plugin.php')
 
+# PHP appends where it read the code from, e.g. `... in Standard input code`
+# or `... in -`. Only that trailing part is noise; ` in ` and ` on ` inside the
+# message itself (`Cannot use isset() on the result of an expression`) are not.
+TRAILING_SOURCE_RE = re.compile(r'\s+in\s+(?:Standard input code|-)\s*$')
+
 
 def _filter_message(message):
     if not message:
         message = 'parse error'
     else:
-        message = message.replace('Standard input code', '')
-        message = message.replace(' on ', '')
-        message = message.replace(' in -', '')
-        message = message.replace(' in ', '')
-        message = message.strip()
+        message = TRAILING_SOURCE_RE.sub('', message).strip()
 
     return message
 
diff --git a/tests/test_regex.py b/tests/test_regex.py
index 5542a50..bda56d1 100644
--- a/tests/test_regex.py
+++ b/tests/test_regex.py
@@ -69,3 +69,36 @@ def test_issue_29(self):
                 'near': None,
             },
         )
+
+    def test_issue_55_message_filter_only_strips_trailing_source(self):
+        # " on " and " in " inside the message must survive
+        self.assertMatch(
+            'Fatal error: Cannot use isset() on the result of an expression '
+            '(you can use "null !== expression" instead) in Standard input code on line 2',
+            {
+                'error': 'Fatal',
+                'line': 1,
+                'message': 'Cannot use isset() on the result of an expression '
+                           '(you can use "null !== expression" instead)',
+            },
+        )
+
+        self.assertMatch(
+            "Fatal error: 'break' not in the 'loop' or 'switch' context "
+            'in Standard input code on line 3',
+            {
+                'error': 'Fatal',
+                'line': 2,
+                'message': "'break' not in the 'loop' or 'switch' context",
+            },
+        )
+
+        self.assertMatch(
+            'Fatal error: Cannot redeclare f() (previously declared in Standard input code:2) '
+            'in Standard input code on line 3',
+            {
+                'error': 'Fatal',
+                'line': 2,
+                'message': 'Cannot redeclare f() (previously declared in Standard input code:2)',
+            },
+        )