diff --git a/src/indexer.cc b/src/indexer.cc
index 50bb299c..68d3f810 100644
--- a/src/indexer.cc
+++ b/src/indexer.cc
@@ -28,6 +28,14 @@
 
 using namespace clang;
 
+#if LLVM_VERSION_MAJOR >= 18 // llvmorg-18-init-10631-gedd690b02e16
+#define TTK_Class TagTypeKind::Class
+#define TTK_Enum TagTypeKind::Enum
+#define TTK_Interface TagTypeKind::Interface
+#define TTK_Struct TagTypeKind::Struct
+#define TTK_Union TagTypeKind::Union
+#endif
+
 namespace ccls {
 namespace {
 
diff --git a/src/messages/textDocument_completion.cc b/src/messages/textDocument_completion.cc
index 8a7394ef..ce769d4d 100644
--- a/src/messages/textDocument_completion.cc
+++ b/src/messages/textDocument_completion.cc
@@ -17,6 +17,10 @@
 #include <regex>
 #endif
 
+#if LLVM_VERSION_MAJOR >= 18 // llvmorg-18-init-10631-gedd690b02e16
+#define TTK_Struct TagTypeKind::Struct
+#endif
+
 namespace ccls {
 using namespace clang;
 using namespace llvm;