diff --git a/clang-tools-extra/clangd/index/SymbolCollector.cpp b/clang-tools-extra/clangd/index/SymbolCollector.cpp
--- a/clang-tools-extra/clangd/index/SymbolCollector.cpp
+++ b/clang-tools-extra/clangd/index/SymbolCollector.cpp
@@ -302,7 +302,7 @@
   if (D->getFriendObjectKind() != Decl::FriendObjectKind::FOK_None)
     D = CanonicalDecls.try_emplace(D, ASTNode.OrigD).first->second;
   const NamedDecl *ND = dyn_cast<NamedDecl>(D);
-  if (!ND)
+  if (!ND || ND->getLocation().isInvalid())
     return true;
 
   // Mark D as referenced if this is a reference coming from the main file.
@@ -540,6 +540,7 @@
   S.SymInfo = index::getSymbolInfo(&ND);
   std::string FileURI;
   auto Loc = findNameLoc(&ND);
+  assert(Loc.isValid() && "Invalid source location for NamedDecl");
   // FIXME: use the result to filter out symbols.
   shouldIndexFile(SM, SM.getFileID(Loc), Opts, &FilesToIndexCache);
   if (auto DeclLoc =
diff --git a/clang-tools-extra/unittests/clangd/SymbolCollectorTests.cpp b/clang-tools-extra/unittests/clangd/SymbolCollectorTests.cpp
--- a/clang-tools-extra/unittests/clangd/SymbolCollectorTests.cpp
+++ b/clang-tools-extra/unittests/clangd/SymbolCollectorTests.cpp
@@ -1241,6 +1241,14 @@
   EXPECT_THAT(Symbols, Contains(QName("printf")));
 }
 
+TEST_F(SymbolCollectorTest, InvalidSourceLoc) {
+  const char *Header = R"(
+      void operator delete(void*)
+        __attribute__((__externally_visible__));)";
+  runSymbolCollector(Header, /**/ "");
+  EXPECT_THAT(Symbols, IsEmpty());
+}
+
 } // namespace
 } // namespace clangd
 } // namespace clang