diff --git a/.github/scripts/defaults.sh b/.github/scripts/defaults.sh
index f1a27049..576c690b 100755
--- a/.github/scripts/defaults.sh
+++ b/.github/scripts/defaults.sh
@@ -45,7 +45,7 @@ mapping["chipyard-streaming-fir"]=" CONFIG=StreamingFIRRocketConfig"
 mapping["chipyard-streaming-passthrough"]=" CONFIG=StreamingPassthroughRocketConfig"
 mapping["chipyard-hetero"]=" CONFIG=LargeBoomAndRocketConfig"
 mapping["chipyard-boom"]=" CONFIG=MediumBoomCosimConfig"
-mapping["chipyard-spike"]=" CONFIG=SpikeConfig"
+mapping["chipyard-spike"]=" CONFIG=SpikeFastUARTConfig EXTRA_SIM_FLAGS='+spike-ipc=10'"
 mapping["chipyard-blkdev"]=" CONFIG=SimBlockDeviceRocketConfig"
 mapping["chipyard-hwacha"]=" CONFIG=HwachaRocketConfig"
 mapping["chipyard-gemmini"]=" CONFIG=GemminiRocketConfig"