Index: clang-tools-extra/trunk/clang-tidy/modernize/UseDefaultMemberInitCheck.cpp
===================================================================
--- clang-tools-extra/trunk/clang-tidy/modernize/UseDefaultMemberInitCheck.cpp
+++ clang-tools-extra/trunk/clang-tidy/modernize/UseDefaultMemberInitCheck.cpp
@@ -158,7 +158,7 @@
             unaryOperator(anyOf(hasOperatorName("+"), hasOperatorName("-")),
                           hasUnaryOperand(floatLiteral())),
             cxxBoolLiteral(), cxxNullPtrLiteralExpr(), implicitValueInitExpr(),
-            declRefExpr());
+            declRefExpr(to(enumConstantDecl())));
 
   Finder->addMatcher(
       cxxConstructorDecl(
Index: clang-tools-extra/trunk/test/clang-tidy/modernize-use-default-member-init.cpp
===================================================================
--- clang-tools-extra/trunk/test/clang-tidy/modernize-use-default-member-init.cpp
+++ clang-tools-extra/trunk/test/clang-tidy/modernize-use-default-member-init.cpp
@@ -221,6 +221,12 @@
   int i;
 };
 
+struct NegativeDefaultArg
+{
+  NegativeDefaultArg(int i = 4) : i(i) {}
+  int i;
+};
+
 struct ExistingChar {
   ExistingChar(short) : e1(), e2(), e3(), e4() {}
   // CHECK-MESSAGES: :[[@LINE-1]]:25: warning: member initializer for 'e1' is redundant [modernize-use-default-member-init]