diff --git a/kernel/cellaigs.cc b/kernel/cellaigs.cc
index 5fd76afe5..26c625f89 100644
--- a/kernel/cellaigs.cc
+++ b/kernel/cellaigs.cc
@@ -453,7 +453,7 @@ Aig::Aig(Cell *cell)
 		int B = mk.inport("\\B");
 		int C = mk.inport("\\C");
 		int D = mk.inport("\\D");
-		int Y = mk.nand_gate(mk.nor_gate(A, B), mk.nor_gate(C, D));
+		int Y = mk.nand_gate(mk.or_gate(A, B), mk.or_gate(C, D));
 		mk.outport(Y, "\\Y");
 		goto optimize;
 	}
diff --git a/kernel/celltypes.h b/kernel/celltypes.h
index ae88f4aaf..0da78c313 100644
--- a/kernel/celltypes.h
+++ b/kernel/celltypes.h
@@ -464,7 +464,7 @@ struct CellTypes
 		if (cell->type == "$_AOI4_")
 			return eval_not(const_or(const_and(arg1, arg2, false, false, 1), const_and(arg3, arg4, false, false, 1), false, false, 1));
 		if (cell->type == "$_OAI4_")
-			return eval_not(const_and(const_or(arg1, arg2, false, false, 1), const_and(arg3, arg4, false, false, 1), false, false, 1));
+			return eval_not(const_and(const_or(arg1, arg2, false, false, 1), const_or(arg3, arg4, false, false, 1), false, false, 1));
 
 		log_assert(arg4.bits.size() == 0);
 		return eval(cell, arg1, arg2, arg3, errp);