diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index 09d1732739b8e..17298dad45640 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -3407,7 +3407,7 @@ void Parser::ParseDeclarationSpecifiers(DeclSpec &DS,
       if (!TypeRep) {
         if (TryAnnotateTypeConstraint())
           goto DoneWithDeclSpec;
-        if (isTypeConstraintAnnotation())
+        if (Tok.isNot(tok::identifier))
           continue;
         if (Tok.is(tok::annot_template_id))
           // Might have been annotated by TryAnnotateTypeConstraint.
diff --git a/clang/test/SemaTemplate/undeclared-template.cpp b/clang/test/SemaTemplate/undeclared-template.cpp
new file mode 100644
index 0000000000000..fccc29deea254
--- /dev/null
+++ b/clang/test/SemaTemplate/undeclared-template.cpp
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 -std=c++2a -verify %s
+
+template<typename T> notdefined<T::any> PR45207; // expected-error {{no template named 'notdefined'}}
+
+// FIXME: We don't disambiguate this as an undeclared template-id even though there's nothing else it could be.
+template<typename T> int var_template(notdefined<T::any>); // expected-error {{undeclared identifier 'notdefined'}} expected-error {{expected expression}}
+
+// FIXME: We don't disambiguate this as a function template even though it can't be a variable template due to the ', int'.
+template<typename T> int fn_template(notdefined<T::any>, int); // expected-error {{undeclared identifier 'notdefined'}} expected-error {{expected expression}} expected-error {{expected '('}}