diff --git a/clang-tools-extra/test/clang-tidy/check_clang_tidy.py b/clang-tools-extra/test/clang-tidy/check_clang_tidy.py
--- a/clang-tools-extra/test/clang-tidy/check_clang_tidy.py
+++ b/clang-tools-extra/test/clang-tidy/check_clang_tidy.py
@@ -119,9 +119,12 @@
     has_check_messages = has_check_messages or has_check_message
     has_check_notes = has_check_notes or has_check_note
 
-    check_fixes_prefixes.append(check_fixes_prefix)
-    check_messages_prefixes.append(check_messages_prefix)
-    check_notes_prefixes.append(check_notes_prefix)
+    if has_check_fix:
+      check_fixes_prefixes.append(check_fixes_prefix)
+    if has_check_message:
+      check_messages_prefixes.append(check_messages_prefix)
+    if has_check_note:
+      check_notes_prefixes.append(check_notes_prefix)
 
   assert has_check_fixes or has_check_messages or has_check_notes
   # Remove the contents of the CHECK lines to avoid CHECKs matching on
diff --git a/clang-tools-extra/test/clang-tidy/checkers/modernize-loop-convert-reverse.cpp b/clang-tools-extra/test/clang-tidy/checkers/modernize-loop-convert-reverse.cpp
--- a/clang-tools-extra/test/clang-tidy/checkers/modernize-loop-convert-reverse.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/modernize-loop-convert-reverse.cpp
@@ -30,13 +30,6 @@
 // RUN:   | FileCheck %s -check-prefix=CHECK-HEADER-NO-FUNC \
 // RUN:       -implicit-check-not="{{warning|error}}:"
 
-/// Suppress FileCheck --allow-unused-prefixes=false diagnostics.
-// CHECK-MESSAGES-RANGES: {{^}}
-// CHECK-MESSAGES-CUSTOM: {{^}}
-// CHECK-MESSAGES-CUSTOM-SYS: {{^}}
-// CHECK-MESSAGES-CUSTOM-NO-SYS: {{^}}
-// CHECK-MESSAGES-CUSTOM-NO-HEADER: {{^}}
-
 // CHECK-HEADER-NO-FUNC: warning: modernize-loop-convert: 'MakeReverseRangeHeader' is set but 'MakeReverseRangeFunction' is not, disabling reverse loop transformation
 
 // Make sure appropiate headers are included