diff --git a/passes/cmds/splitcells.cc b/passes/cmds/splitcells.cc
index 074bf0f64..e3d509564 100644
--- a/passes/cmds/splitcells.cc
+++ b/passes/cmds/splitcells.cc
@@ -103,8 +103,7 @@ struct SplitcellsWorker
 
 				auto slice_signal = [&](SigSpec old_sig) -> SigSpec {
 					SigSpec new_sig;
-					for (int i = 0; i < GetSize(old_sig); i += GetSize(outsig)) {
-						int offset = i+slice_lsb;
+					for (int offset = slice_lsb; offset <= GetSize(old_sig); offset += GetSize(outsig)) {
 						int length = std::min(GetSize(old_sig)-offset, slice_msb-slice_lsb+1);
 						new_sig.append(old_sig.extract(offset, length));
 					}