diff --git a/src/main/kotlin/me/zhouxi/slint/lsp/SlintLspServerSupportProvider.kt b/src/main/kotlin/me/zhouxi/slint/lsp/SlintLspServerSupportProvider.kt
index 2a762fd..f1ccb7b 100644
--- a/src/main/kotlin/me/zhouxi/slint/lsp/SlintLspServerSupportProvider.kt
+++ b/src/main/kotlin/me/zhouxi/slint/lsp/SlintLspServerSupportProvider.kt
@@ -9,6 +9,7 @@ import com.intellij.platform.lsp.api.ProjectWideLspServerDescriptor
 import com.intellij.platform.lsp.api.lsWidget.LspServerWidgetItem
 import me.zhouxi.slint.SlintRuntime
 import me.zhouxi.slint.icons.SlintIcons
+import me.zhouxi.slint.lang.SlintFileType
 
 class SlintLspServerSupportProvider : LspServerSupportProvider {
     override fun fileOpened(
@@ -16,8 +17,8 @@ class SlintLspServerSupportProvider : LspServerSupportProvider {
         file: VirtualFile,
         serverStarter: LspServerSupportProvider.LspServerStarter
     ) {
-        if (file.extension == "slint") {
-            serverStarter.ensureServerStarted(FooLspServerDescriptor(project))
+        if (file.fileType == SlintFileType) {
+            serverStarter.ensureServerStarted(SlintLspServerDescriptor(project))
         }
     }
 
@@ -31,8 +32,8 @@ class SlintLspServerSupportProvider : LspServerSupportProvider {
             SlintIcons.Primary,
         )
 
-    private class FooLspServerDescriptor(project: Project) : ProjectWideLspServerDescriptor(project, "Slint") {
-        override fun isSupportedFile(file: VirtualFile) = file.extension == "slint"
+    private class SlintLspServerDescriptor(project: Project) : ProjectWideLspServerDescriptor(project, "Slint") {
+        override fun isSupportedFile(file: VirtualFile) = file.fileType == SlintFileType
         override fun createCommandLine(): GeneralCommandLine {
             val line = GeneralCommandLine(SlintRuntime.LspExecutable.toAbsolutePath().toString())