diff --git a/examples/helloworld_ecp5.nix b/examples/helloworld_ecp5.nix
index 151ef85..98fc76a 100644
--- a/examples/helloworld_ecp5.nix
+++ b/examples/helloworld_ecp5.nix
@@ -17,7 +17,7 @@ let
     IOBUF PORT "serial_tx" IO_TYPE=LVCMOS33;
     EOF
 
-    echo -n "--um-45k --package CABGA381" > $out/device
+    echo -n "--um-45k --speed 8 --package CABGA381" > $out/device
     '';
 in
   hx.symbiflow.buildBitstream {
diff --git a/examples/simplesoc_ecp5.nix b/examples/simplesoc_ecp5.nix
index 586c6e4..9935c1a 100644
--- a/examples/simplesoc_ecp5.nix
+++ b/examples/simplesoc_ecp5.nix
@@ -17,7 +17,7 @@ let
     IOBUF PORT "serial_tx" IO_TYPE=LVCMOS33;
     EOF
 
-    echo -n "--um-45k --package CABGA381" > $out/device
+    echo -n "--um-45k --speed 8 --package CABGA381" > $out/device
     '';
 in
   hx.symbiflow.buildBitstream {