diff --git a/.changeset/wise-grapes-try.md b/.changeset/wise-grapes-try.md
new file mode 100644
index 00000000..9dc65fcd
--- /dev/null
+++ b/.changeset/wise-grapes-try.md
@@ -0,0 +1,5 @@
+---
+"@cartesi/sdk": patch
+---
+
+eth_isready won't fail without a block number
diff --git a/packages/sdk/eth_isready b/packages/sdk/eth_isready
index f0c38958..8ab9ea23 100755
--- a/packages/sdk/eth_isready
+++ b/packages/sdk/eth_isready
@@ -1,10 +1,11 @@
 #!/usr/bin/env sh
-set -eu
+set -euo pipefail
 
 RPC_URL="${RPC_URL:-http://127.0.0.1:8545}"
+BLOCK_NUMBER=${1:-}
 
 # If a block number argument is provided, check that the chain has reached it
-if [ -n "$1" ]; then
+if [ -n "$BLOCK_NUMBER" ]; then
     current=$(cast block-number --rpc-url "$RPC_URL" 2>/dev/null) || exit 1
     target=$(($1))
     [ "$current" -ge "$target" ] && exit 0 || exit 1