diff --git a/passes/cmds/check.cc b/passes/cmds/check.cc
index 178653c41..152eabcd9 100644
--- a/passes/cmds/check.cc
+++ b/passes/cmds/check.cc
@@ -290,6 +290,9 @@ struct CheckPass : public Pass {
 			pool<Cell *> coarsened_cells;
 			for (auto cell : module->cells())
 			{
+				if (cell->type == ID($input_port))
+					continue;
+
 				if (mapped && cell->type.begins_with("$") && design->module(cell->type) == nullptr) {
 					if (allow_tbuf && cell->type == ID($_TBUF_)) goto cell_allowed;
 					log_warning("Cell %s.%s is an unmapped internal cell of type %s.\n", module, cell, cell->type.unescape());