diff --git a/ice40/arch.cc b/ice40/arch.cc
index fbad6ab0..6bca62e4 100644
--- a/ice40/arch.cc
+++ b/ice40/arch.cc
@@ -494,6 +494,15 @@ bool Arch::getCellDelay(const CellInfo *cell, IdString fromPort, IdString toPort
                 delay = 450;
                 return true;
             }
+        } else if (fromPort == id("CI") && toPort == id("CO")) {
+            delay = 120;
+            return true;
+        } else if (fromPort == id("I1") && toPort == id("CO")) {
+            delay = 260;
+            return true;
+        } else if (fromPort == id("I2") && toPort == id("CO")) {
+            delay = 230;
+            return true;
         }
     }
     return false;