Index: clang-tools-extra/clang-tidy/modernize/MacroToEnumCheck.cpp
===================================================================
--- clang-tools-extra/clang-tidy/modernize/MacroToEnumCheck.cpp
+++ clang-tools-extra/clang-tidy/modernize/MacroToEnumCheck.cpp
@@ -278,20 +278,17 @@
   }
 }
 
+inline StringRef getTokenName(const Token &Tok) {
+  return Tok.is(tok::raw_identifier) ? Tok.getRawIdentifier()
+                                     : Tok.getIdentifierInfo()->getName();
+}
+
 void MacroToEnumCallbacks::checkName(const Token &MacroNameTok) {
-  std::string Id;
-  if (MacroNameTok.is(tok::raw_identifier))
-    Id = MacroNameTok.getRawIdentifier().str();
-  else if (MacroNameTok.is(tok::identifier))
-    Id = MacroNameTok.getIdentifierInfo()->getName().str();
-  else {
-    assert(false && "Expected either an identifier or raw identifier token");
-    return;
-  }
+  std::string Id = getTokenName(MacroNameTok).str();
 
   llvm::erase_if(Enums, [&Id](const MacroList &MacroList) {
     return llvm::any_of(MacroList, [&Id](const EnumMacro &Macro) {
-      return Macro.Name.getIdentifierInfo()->getName().str() == Id;
+      return getTokenName(Macro.Name).str() == Id;
     });
   });
 }
@@ -355,8 +352,7 @@
                                           const MacroDefinition &MD,
                                           const MacroDirective *Undef) {
   auto MatchesToken = [&MacroNameTok](const EnumMacro &Macro) {
-    return Macro.Name.getIdentifierInfo()->getName() ==
-           MacroNameTok.getIdentifierInfo()->getName();
+    return getTokenName(Macro.Name) == getTokenName(MacroNameTok);
   };
 
   auto It = llvm::find_if(Enums, [MatchesToken](const MacroList &MacroList) {
@@ -432,8 +428,8 @@
 
 void MacroToEnumCallbacks::warnMacroEnum(const EnumMacro &Macro) const {
   Check->diag(Macro.Directive->getLocation(),
-              "macro %0 defines an integral constant; prefer an enum instead")
-      << Macro.Name.getIdentifierInfo();
+              "macro '%0' defines an integral constant; prefer an enum instead")
+      << getTokenName(Macro.Name).str();
 }
 
 void MacroToEnumCallbacks::fixEnumMacro(const MacroList &MacroList) const {
Index: clang-tools-extra/test/clang-tidy/checkers/modernize-macro-to-enum.cpp
===================================================================
--- clang-tools-extra/test/clang-tidy/checkers/modernize-macro-to-enum.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/modernize-macro-to-enum.cpp
@@ -208,6 +208,10 @@
 #define IFNDEF3 3
 #endif
 
+// Sometimes an argument to ifdef can be classified as a keyword token.
+#ifdef __restrict
+#endif
+
 // These macros do not expand to integral constants.
 #define HELLO "Hello, "
 #define WORLD "World"