diff --git a/Source/Tools/Flax.Build/Build/Assembler.cs b/Source/Tools/Flax.Build/Build/Assembler.cs
index ec428d7bb..fe95a505d 100644
--- a/Source/Tools/Flax.Build/Build/Assembler.cs
+++ b/Source/Tools/Flax.Build/Build/Assembler.cs
@@ -83,6 +83,7 @@ namespace Flax.Build
                 }
                 
                 // Skip when project references were changed
+                if (Globals.Project != null)
                 {
                     DateTime lastWriteTime = File.GetLastWriteTime(Globals.Project.ProjectPath);
                     if (lastWriteTime > recentWriteTime)