diff --git a/Cargo.toml b/Cargo.toml
index 93968b4..a3b0906 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -16,8 +16,8 @@ thiserror = "2.0.12"
 [dev-dependencies]
 proptest = "1.7.0"
 similar-asserts = "1.7.0"
-cap-std = "3.4.4"
-sha2 = "0.10.9"
+cap-std = "4.0.0"
+sha2 = "0.11.0"
 # For cross-integration testing
 olpc-cjson = "0.1"
 cjson = "0.1.2"
diff --git a/src/lib.rs b/src/lib.rs
index 0f2458f..087aa52 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -679,7 +679,12 @@ mod tests {
             // testdata sha256sum are computed with a trailing \n
             sha256.update("\n");
             let filename = filename.trim_end_matches(".json");
-            let hash = format!("{:x}", sha256.finalize());
+            let digest = sha256.finalize();
+            let hash = digest.iter().fold(String::new(), |mut s, b| {
+                use std::fmt::Write;
+                write!(s, "{b:02x}").unwrap();
+                s
+            });
             assert_eq!(filename, hash);
             let json2: serde_json::Value = serde_json::from_slice(&enc)?;