diff --git a/kernel/rtlil.cc b/kernel/rtlil.cc
index f741e2a34..6bb395ec2 100644
--- a/kernel/rtlil.cc
+++ b/kernel/rtlil.cc
@@ -1866,7 +1866,7 @@ void RTLIL::SigSpec::extend(int width, bool is_signed)
 
 void RTLIL::SigSpec::extend_u0(int width, bool is_signed)
 {
-	cover("kernel.rtlil.sigspec.extend_0");
+	cover("kernel.rtlil.sigspec.extend_u0");
 
 	pack();