diff --git a/clang-tools-extra/clangd/index/Index.h b/clang-tools-extra/clangd/index/Index.h
--- a/clang-tools-extra/clangd/index/Index.h
+++ b/clang-tools-extra/clangd/index/Index.h
@@ -94,31 +94,6 @@
 }
 llvm::raw_ostream &operator<<(llvm::raw_ostream &, const SymbolLocation &);
 
-} // namespace clangd
-} // namespace clang
-namespace llvm {
-// Support SymbolIDs as DenseMap keys.
-template <> struct DenseMapInfo<clang::clangd::SymbolID> {
-  static inline clang::clangd::SymbolID getEmptyKey() {
-    static clang::clangd::SymbolID EmptyKey("EMPTYKEY");
-    return EmptyKey;
-  }
-  static inline clang::clangd::SymbolID getTombstoneKey() {
-    static clang::clangd::SymbolID TombstoneKey("TOMBSTONEKEY");
-    return TombstoneKey;
-  }
-  static unsigned getHashValue(const clang::clangd::SymbolID &Sym) {
-    return hash_value(Sym);
-  }
-  static bool isEqual(const clang::clangd::SymbolID &LHS,
-                      const clang::clangd::SymbolID &RHS) {
-    return LHS == RHS;
-  }
-};
-} // namespace llvm
-namespace clang {
-namespace clangd {
-
 // Describes the source of information about a symbol.
 // Mainly useful for debugging, e.g. understanding code completion reuslts.
 // This is a bitfield as information can be combined from several sources.
diff --git a/clang-tools-extra/clangd/index/SymbolID.h b/clang-tools-extra/clangd/index/SymbolID.h
--- a/clang-tools-extra/clangd/index/SymbolID.h
+++ b/clang-tools-extra/clangd/index/SymbolID.h
@@ -9,6 +9,7 @@
 #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_SYMBOLID_H
 #define LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_SYMBOLID_H
 
+#include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/Hashing.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Error.h"
@@ -61,4 +62,25 @@
 } // namespace clangd
 } // namespace clang
 
+namespace llvm {
+// Support SymbolIDs as DenseMap keys.
+template <> struct DenseMapInfo<clang::clangd::SymbolID> {
+  static inline clang::clangd::SymbolID getEmptyKey() {
+    static clang::clangd::SymbolID EmptyKey("EMPTYKEY");
+    return EmptyKey;
+  }
+  static inline clang::clangd::SymbolID getTombstoneKey() {
+    static clang::clangd::SymbolID TombstoneKey("TOMBSTONEKEY");
+    return TombstoneKey;
+  }
+  static unsigned getHashValue(const clang::clangd::SymbolID &Sym) {
+    return hash_value(Sym);
+  }
+  static bool isEqual(const clang::clangd::SymbolID &LHS,
+                      const clang::clangd::SymbolID &RHS) {
+    return LHS == RHS;
+  }
+};
+} // namespace llvm
+
 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_SYMBOLID_H