diff --git a/gatemate/chip.py b/gatemate/chip.py
index c2d9ad9..62da6da 100644
--- a/gatemate/chip.py
+++ b/gatemate/chip.py
@@ -105,7 +105,7 @@ class Chip:
         die_num = x_die + y_die * self.die_width
         return die.get_tile_info(die_num, x_pos, y_pos)
 
-    def create_conn(self, conn, src_x,src_y, src, dst_x, dst_y, dst, delay=""):
+    def create_conn(self, conn, src_x,src_y, src, dst_x, dst_y, dst, delay="del_dummy"):
         key_val = f"{src_x}/{src_y}/{src}"
         key  = Connection(src_x, src_y, src, "",   False)
         item = Connection(dst_x, dst_y, dst, delay,True)
diff --git a/gatemate/die.py b/gatemate/die.py
index 4e4a248..bca1d28 100644
--- a/gatemate/die.py
+++ b/gatemate/die.py
@@ -3752,7 +3752,7 @@ class Die:
                     self.gpio_to_loc[f"GPIO_{io.bank}_{io.port}[{io.num}]"]  = Location(x, y, 0)
                     self.io_pad_names[io.bank][io.port][io.num] = Location(x, y, 0)
 
-    def create_conn(self, src_x,src_y, src, dst_x, dst_y, dst, delay=""):
+    def create_conn(self, src_x,src_y, src, dst_x, dst_y, dst, delay="del_dummy"):
         key_val = f"{src_x + self.offset_x}/{src_y + self.offset_y}/{src}"
         key  = Connection(src_x + self.offset_x, src_y + self.offset_y, src, ""   , False)
         item = Connection(dst_x + self.offset_x, dst_y + self.offset_y, dst, delay, True)