diff --git a/Src/AST/Myc.Ast.RTL.TypeRegistry.pas b/Src/AST/Myc.Ast.RTL.TypeRegistry.pas
index 50ea1a0..874897d 100644
--- a/Src/AST/Myc.Ast.RTL.TypeRegistry.pas
+++ b/Src/AST/Myc.Ast.RTL.TypeRegistry.pas
@@ -113,15 +113,20 @@ end;
 
 class procedure TRtlTypeRegistry.RegisterType(Info: PTypeInfo);
 begin
-    if FKnownTypes.ContainsKey(Info) then
-        exit;
-
-    EnterAnalysis(Info);
+    TMonitor.Enter(FKnownTypes);
     try
-        var staticType := AnalyzeType(Info);
-        FKnownTypes.Add(Info, staticType);
+        if FKnownTypes.ContainsKey(Info) then
+            exit;
+
+        EnterAnalysis(Info);
+        try
+            var staticType := AnalyzeType(Info);
+            FKnownTypes.Add(Info, staticType);
+        finally
+            ExitAnalysis(Info);
+        end;
     finally
-        ExitAnalysis(Info);
+        TMonitor.Exit(FKnownTypes);
     end;
 end;