diff --git a/r/org.eclipse.statet.nico.ui/src/org/eclipse/statet/nico/ui/console/GenericConsoleSourceUnit.java b/r/org.eclipse.statet.nico.ui/src/org/eclipse/statet/nico/ui/console/GenericConsoleSourceUnit.java
index a0b017d..461843c 100644
--- a/r/org.eclipse.statet.nico.ui/src/org/eclipse/statet/nico/ui/console/GenericConsoleSourceUnit.java
+++ b/r/org.eclipse.statet.nico.ui/src/org/eclipse/statet/nico/ui/console/GenericConsoleSourceUnit.java
@@ -141,7 +141,7 @@
 	}
 	
 	@Override
-	public long getContentStamp(final IProgressMonitor monitor) {
+	public long getContentStamp(final @Nullable IProgressMonitor monitor) {
 		return this.document.getModificationStamp();
 	}