diff --git a/Cargo.toml b/Cargo.toml
index 510dde7af..e046c799f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -36,7 +36,7 @@ downcast-rs = "1.2.0"
 enum_dispatch = "0.3.11"
 html-escape = "0.2.13"
 itertools = "0.13.0"
-jsonschema = "0.24.0"
+jsonschema = "0.26.0"
 lazy_static = "1.4.0"
 num-rational = "0.4.1"
 paste = "1.0"
diff --git a/hugr-core/src/hugr/serialize/test.rs b/hugr-core/src/hugr/serialize/test.rs
index 22ae2895c..4da2197ef 100644
--- a/hugr-core/src/hugr/serialize/test.rs
+++ b/hugr-core/src/hugr/serialize/test.rs
@@ -54,7 +54,8 @@ impl NamedSchema {
     }
 
     pub fn check(&self, val: &serde_json::Value) {
-        if let Err(errors) = self.schema.validate(val) {
+        let mut errors = self.schema.iter_errors(val).peekable();
+        if errors.peek().is_some() {
             // errors don't necessarily implement Debug
             eprintln!("Schema failed to validate: {}", self.name);
             for error in errors {