diff --git a/clang/lib/Format/UnwrappedLineParser.cpp b/clang/lib/Format/UnwrappedLineParser.cpp
--- a/clang/lib/Format/UnwrappedLineParser.cpp
+++ b/clang/lib/Format/UnwrappedLineParser.cpp
@@ -3530,9 +3530,9 @@
       // concept C = bool(...);
       // and bool is the only type, all other types as cast must be inside a
       // cast to bool an thus are handled by the other cases.
-      nextToken();
-      if (FormatTok->isNot(tok::l_paren))
+      if (Tokens->peekNextToken()->isNot(tok::l_paren))
         return;
+      nextToken();
       parseParens();
       break;
 
diff --git a/clang/unittests/Format/TokenAnnotatorTest.cpp b/clang/unittests/Format/TokenAnnotatorTest.cpp
--- a/clang/unittests/Format/TokenAnnotatorTest.cpp
+++ b/clang/unittests/Format/TokenAnnotatorTest.cpp
@@ -449,6 +449,14 @@
   EXPECT_TRUE(Tokens[14]->ClosesRequiresClause);
   EXPECT_TOKEN(Tokens[20], tok::arrow, TT_TrailingReturnArrow);
 
+  Tokens = annotate("template <typename T>\n"
+                    "requires Bar<T>\n"
+                    "bool foo(T) { return false; }");
+  ASSERT_EQ(Tokens.size(), 21u) << Tokens;
+  EXPECT_TOKEN(Tokens[5], tok::kw_requires, TT_RequiresClause);
+  EXPECT_TRUE(Tokens[9]->ClosesRequiresClause);
+  EXPECT_TOKEN(Tokens[11], tok::identifier, TT_FunctionDeclarationName);
+
   Tokens = annotate("template <typename T>\n"
                     "struct S {\n"
                     "  void foo() const requires Bar<T>;\n"