diff --git a/iwyu.cc b/iwyu.cc
index 392e1f5..74adb95 100644
--- a/iwyu.cc
+++ b/iwyu.cc
@@ -1,4 +1,4 @@
-//===--- iwyu.cpp - main logic and driver for include-what-you-use --------===//
+//===--- iwyu.cc - main logic and driver for include-what-you-use ---------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/iwyu_ast_util.cc b/iwyu_ast_util.cc
index 6db26c5..9c97749 100644
--- a/iwyu_ast_util.cc
+++ b/iwyu_ast_util.cc
@@ -1,4 +1,4 @@
-//===--- iwyu_ast_util.h - clang-AST utilities for include-what-you-use ---===//
+//===--- iwyu_ast_util.cc - clang-AST utilities for include-what-you-use --===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/iwyu_cache.cc b/iwyu_cache.cc
index ae7c952..6aee9bc 100644
--- a/iwyu_cache.cc
+++ b/iwyu_cache.cc
@@ -1,4 +1,4 @@
-//===--- iwyu_cache.cpp - cache of AST-derived information, for iwyu ------===//
+//===--- iwyu_cache.cc - cache of AST-derived information, for iwyu -------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/iwyu_globals.cc b/iwyu_globals.cc
index c9e567b..8c86c36 100644
--- a/iwyu_globals.cc
+++ b/iwyu_globals.cc
@@ -1,4 +1,4 @@
-//===--- iwyu_string_util.cpp - global variables for include-what-you-use -===//
+//===--- iwyu_globals.cc - global variables for include-what-you-use ------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/iwyu_globals.h b/iwyu_globals.h
index 3dec3db..36a231b 100644
--- a/iwyu_globals.h
+++ b/iwyu_globals.h
@@ -1,4 +1,4 @@
-//===--- iwyu_string_util.h - global variables for include-what-you-use ---===//
+//===--- iwyu_globals.h - global variables for include-what-you-use -------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/iwyu_include_picker.cc b/iwyu_include_picker.cc
index cabd6f9..b0a85b6 100644
--- a/iwyu_include_picker.cc
+++ b/iwyu_include_picker.cc
@@ -1,4 +1,4 @@
-//===--- iwyu_include_picker.cpp - map to canonical #includes for iwyu ----===//
+//===--- iwyu_include_picker.cc - map to canonical #includes for iwyu -----===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/iwyu_lexer_utils.cc b/iwyu_lexer_utils.cc
index 81f57e4..dba1753 100644
--- a/iwyu_lexer_utils.cc
+++ b/iwyu_lexer_utils.cc
@@ -1,4 +1,4 @@
-//===--- iwyu_lexer_utils.cpp - clang-lexer utilities for iwyu ------------===//
+//===--- iwyu_lexer_utils.cc - clang-lexer utilities for iwyu -------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/iwyu_location_util.cc b/iwyu_location_util.cc
index c9d5e3c..9de94cc 100644
--- a/iwyu_location_util.cc
+++ b/iwyu_location_util.cc
@@ -1,4 +1,4 @@
-//===--- iwyu_location_util.cpp - SourceLoc-related utilities for iwyu ----===//
+//===--- iwyu_location_util.cc - SourceLoc-related utilities for iwyu -----===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/iwyu_output.cc b/iwyu_output.cc
index 1a84e56..ec9f8f2 100644
--- a/iwyu_output.cc
+++ b/iwyu_output.cc
@@ -1,4 +1,4 @@
-//===--- iwyu_output.cpp - output-emitting code for include-what-you-use --===//
+//===--- iwyu_output.cc - output-emitting code for include-what-you-use ---===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/iwyu_path_util.cc b/iwyu_path_util.cc
index 53f82ba..0043363 100644
--- a/iwyu_path_util.cc
+++ b/iwyu_path_util.cc
@@ -1,4 +1,4 @@
-//===--- iwyu_path_util.cc - path utilities for iwyu ----===//
+//===--- iwyu_path_util.cc - file-path utilities for include-what-you-use -===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/iwyu_preprocessor.cc b/iwyu_preprocessor.cc
index a3f17a9..128acca 100644
--- a/iwyu_preprocessor.cc
+++ b/iwyu_preprocessor.cc
@@ -1,4 +1,4 @@
-//===--- iwyu_preprocessor.cpp - handle #includes/#defines for iwyu -------===//
+//===--- iwyu_preprocessor.cc - handle #includes/#defines for iwyu --------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/iwyu_verrs.cc b/iwyu_verrs.cc
index 8995f3a..220ed00 100644
--- a/iwyu_verrs.cc
+++ b/iwyu_verrs.cc
@@ -1,4 +1,4 @@
-//===--- iwyu_verrs.h - debug output for include-what-you-use ----===//
+//===--- iwyu_verrs.cc - debug output for include-what-you-use ------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/iwyu_verrs.h b/iwyu_verrs.h
index b816d40..4160454 100644
--- a/iwyu_verrs.h
+++ b/iwyu_verrs.h
@@ -1,4 +1,4 @@
-//===--- iwyu_verrs.h - debug output for include-what-you-use ----===//
+//===--- iwyu_verrs.h - debug output for include-what-you-use -------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/more_tests/iwyu_lexer_utils_test.cc b/more_tests/iwyu_lexer_utils_test.cc
index af2fd8e..1e52fdd 100644
--- a/more_tests/iwyu_lexer_utils_test.cc
+++ b/more_tests/iwyu_lexer_utils_test.cc
@@ -1,4 +1,4 @@
-//===--- iwyu_lexer_utils_test.cpp - test iwyu_lexer_utils.{cc,h} ---------===//
+//===--- iwyu_lexer_utils_test.cc - test iwyu_lexer_utils.{cc,h} ----------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/more_tests/iwyu_output_test.cc b/more_tests/iwyu_output_test.cc
index 434e9d0..4cdd839 100644
--- a/more_tests/iwyu_output_test.cc
+++ b/more_tests/iwyu_output_test.cc
@@ -1,4 +1,4 @@
-//===--- iwyu_output_test.cpp - test iwyu_output.{h,cc} -------------------===//
+//===--- iwyu_output_test.cc - test iwyu_output.{h,cc} --------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/more_tests/iwyu_string_util_test.cc b/more_tests/iwyu_string_util_test.cc
index ce85a37..65e199c 100644
--- a/more_tests/iwyu_string_util_test.cc
+++ b/more_tests/iwyu_string_util_test.cc
@@ -1,4 +1,4 @@
-//===--- iwyu_string_util_test.cpp - test iwyu_string_util.h -------------===//
+//===--- iwyu_string_util_test.cc - test iwyu_string_util.h ---------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/tests/comment_pragmas-d10.h b/tests/comment_pragmas-d10.h
index b2465a7..c6cfb3a 100644
--- a/tests/comment_pragmas-d10.h
+++ b/tests/comment_pragmas-d10.h
@@ -1,4 +1,4 @@
-//===--- comment_pragmas-d10.h - test input file for iwyu ------------------===//
+//===--- comment_pragmas-d10.h - test input file for iwyu -----------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/tests/comment_pragmas-d14.h b/tests/comment_pragmas-d14.h
index bfea934..59a9679 100644
--- a/tests/comment_pragmas-d14.h
+++ b/tests/comment_pragmas-d14.h
@@ -1,4 +1,4 @@
-//===--- comment_pragmas-d14.h - test input file for iwyu ------------------===//
+//===--- comment_pragmas-d14.h - test input file for iwyu -----------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/tests/comment_pragmas-d15.h b/tests/comment_pragmas-d15.h
index 1c23c89..cb766bf 100644
--- a/tests/comment_pragmas-d15.h
+++ b/tests/comment_pragmas-d15.h
@@ -1,4 +1,4 @@
-//===--- comment_pragmas-d15.h - test input file for iwyu ------------------===//
+//===--- comment_pragmas-d15.h - test input file for iwyu -----------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/tests/comment_pragmas-d2.h b/tests/comment_pragmas-d2.h
index fc986e1..1fea695 100644
--- a/tests/comment_pragmas-d2.h
+++ b/tests/comment_pragmas-d2.h
@@ -1,4 +1,4 @@
-//===--- comment_pragmas-d1.h - test input file for iwyu ------------------===//
+//===--- comment_pragmas-d2.h - test input file for iwyu ------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/tests/comment_pragmas-i10.h b/tests/comment_pragmas-i10.h
index f319254..a8cbe71 100644
--- a/tests/comment_pragmas-i10.h
+++ b/tests/comment_pragmas-i10.h
@@ -1,4 +1,4 @@
-//===--- comment_pragmas-i10.h - test input file for iwyu ------------------===//
+//===--- comment_pragmas-i10.h - test input file for iwyu -----------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/tests/comment_pragmas-i11.h b/tests/comment_pragmas-i11.h
index 31ee2d0..3592ff6 100644
--- a/tests/comment_pragmas-i11.h
+++ b/tests/comment_pragmas-i11.h
@@ -1,4 +1,4 @@
-//===--- comment_pragmas-i11.h - test input file for iwyu ------------------===//
+//===--- comment_pragmas-i11.h - test input file for iwyu -----------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/tests/implicit_ctor-d1.h b/tests/implicit_ctor-d1.h
index d258d1f..5252728 100644
--- a/tests/implicit_ctor-d1.h
+++ b/tests/implicit_ctor-d1.h
@@ -1,4 +1,4 @@
-//===--- implicit_ctor-d1.h - test input file for iwyu ---------------------===//
+//===--- implicit_ctor-d1.h - test input file for iwyu --------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/tests/implicit_ctor-i1.h b/tests/implicit_ctor-i1.h
index 48e5905..d557735 100644
--- a/tests/implicit_ctor-i1.h
+++ b/tests/implicit_ctor-i1.h
@@ -1,4 +1,4 @@
-//===--- implicit_ctor-i1.h - test input file for iwyu ---------------------===//
+//===--- implicit_ctor-i1.h - test input file for iwyu --------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/tests/implicit_ctor-i2.h b/tests/implicit_ctor-i2.h
index e31cec3..a978332 100644
--- a/tests/implicit_ctor-i2.h
+++ b/tests/implicit_ctor-i2.h
@@ -1,4 +1,4 @@
-//===--- implicit_ctor-i2.h - test input file for iwyu ---------------------===//
+//===--- implicit_ctor-i2.h - test input file for iwyu --------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/tests/include_with_using-d2.h b/tests/include_with_using-d2.h
index e1c47f6..c479221 100644
--- a/tests/include_with_using-d2.h
+++ b/tests/include_with_using-d2.h
@@ -1,4 +1,4 @@
-//===--- include_with_using-d1.h - test input file for iwyu ---------------===//
+//===--- include_with_using-d2.h - test input file for iwyu ---------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/tests/internal/private.h b/tests/internal/private.h
index bf2b66b..d4a2668 100644
--- a/tests/internal/private.h
+++ b/tests/internal/private.h
@@ -1,4 +1,4 @@
-//===--- internal_files.cc - test input file for iwyu ---------------------===//
+//===--- private.h - test input file for iwyu -----------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/tests/system_namespaces-d2.h b/tests/system_namespaces-d2.h
index 3946740..2a5b033 100644
--- a/tests/system_namespaces-d2.h
+++ b/tests/system_namespaces-d2.h
@@ -1,4 +1,4 @@
-//===--- system_namespaces-d1.h - test input file for iwyu ----------------===//
+//===--- system_namespaces-d2.h - test input file for iwyu ----------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
diff --git a/tests/system_namespaces-d3.h b/tests/system_namespaces-d3.h
index 8d50575..bdc1d83 100644
--- a/tests/system_namespaces-d3.h
+++ b/tests/system_namespaces-d3.h
@@ -1,4 +1,4 @@
-//===--- system_namespaces-d1.h - test input file for iwyu ----------------===//
+//===--- system_namespaces-d3.h - test input file for iwyu ----------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //