diff --git a/clang-tools-extra/clangd/ExpectedTypes.cpp b/clang-tools-extra/clangd/ExpectedTypes.cpp
--- a/clang-tools-extra/clangd/ExpectedTypes.cpp
+++ b/clang-tools-extra/clangd/ExpectedTypes.cpp
@@ -44,12 +44,10 @@
 static llvm::Optional<QualType>
 typeOfCompletion(const CodeCompletionResult &R) {
   const NamedDecl *D = R.Declaration;
-  if (!D)
-    return llvm::None;
   // Templates do not have a type on their own, look at the templated decl.
-  if (auto *Template = dyn_cast<TemplateDecl>(D))
+  if (auto *Template = dyn_cast_or_null<TemplateDecl>(D))
     D = Template->getTemplatedDecl();
-  auto *VD = dyn_cast<ValueDecl>(D);
+  auto *VD = dyn_cast_or_null<ValueDecl>(D);
   if (!VD)
     return llvm::None; // We handle only variables and functions below.
   auto T = VD->getType();
diff --git a/clang-tools-extra/clangd/unittests/CodeCompleteTests.cpp b/clang-tools-extra/clangd/unittests/CodeCompleteTests.cpp
--- a/clang-tools-extra/clangd/unittests/CodeCompleteTests.cpp
+++ b/clang-tools-extra/clangd/unittests/CodeCompleteTests.cpp
@@ -1030,6 +1030,16 @@
                         SnippetSuffix("(${1:int A})"))));
 }
 
+TEST(CompletionTest, NoCrashWithTemplateParamsAndPreferredTypes) {
+  auto Completions = completions(R"cpp(
+template <template <class> class TT> int foo() {
+  int a = ^
+}
+)cpp")
+                         .Completions;
+  EXPECT_THAT(Completions, Contains(Named("TT")));
+}
+
 SignatureHelp signatures(llvm::StringRef Text, Position Point,
                          std::vector<Symbol> IndexSymbols = {}) {
   std::unique_ptr<SymbolIndex> Index;