Index: clang/lib/Format/TokenAnnotator.cpp
===================================================================
--- clang/lib/Format/TokenAnnotator.cpp
+++ clang/lib/Format/TokenAnnotator.cpp
@@ -783,7 +783,7 @@
     OpeningBrace.ParentBracket = Contexts.back().ContextKind;
 
     if (Contexts.back().CaretFound)
-      OpeningBrace.setType(TT_ObjCBlockLBrace);
+      OpeningBrace.overwriteFixedType(TT_ObjCBlockLBrace);
     Contexts.back().CaretFound = false;
 
     ScopedContextCreator ContextCreator(*this, tok::l_brace, 1);
Index: clang/unittests/Format/TokenAnnotatorTest.cpp
===================================================================
--- clang/unittests/Format/TokenAnnotatorTest.cpp
+++ clang/unittests/Format/TokenAnnotatorTest.cpp
@@ -612,6 +612,22 @@
   EXPECT_TOKEN(Tokens[4], tok::r_brace, TT_InlineASMBrace);
 }
 
+TEST_F(TokenAnnotatorTest, UnderstandsObjCBlock) {
+  auto Tokens = annotate("int (^)() = ^ ()\n"
+                         "  external_source_symbol() { //\n"
+                         "  return 1;\n"
+                         "};");
+  ASSERT_EQ(Tokens.size(), 21u) << Tokens;
+  EXPECT_TOKEN(Tokens[1], tok::l_paren, TT_ObjCBlockLParen);
+  EXPECT_TOKEN(Tokens[13], tok::l_brace, TT_ObjCBlockLBrace);
+
+  Tokens = annotate("int *p = ^int*(){ //\n"
+                    "  return nullptr;\n"
+                    "}();");
+  ASSERT_EQ(Tokens.size(), 19u) << Tokens;
+  EXPECT_TOKEN(Tokens[9], tok::l_brace, TT_ObjCBlockLBrace);
+}
+
 } // namespace
 } // namespace format
 } // namespace clang