diff --git a/Cargo.toml b/Cargo.toml
index 44858f71b9c..a29c19212b0 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -218,7 +218,8 @@ either = "1.9"
 enum-as-inner = "0.6"
 enum-map = "2.6.3"
 env_logger = "0.10"
-ethnum = { version = "1.5.0", features = ["serde"] }
+# This must be at least 1.5.3. See https://github.com/clockworklabs/SpacetimeDB/issues/5512.
+ethnum = { version = "1.5.3", features = ["serde"] }
 flate2 = "1.0.24"
 foldhash = "0.2.0"
 fs-err = "2.9.0"