diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7e6de8b..52ca750 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,7 +1,8 @@
 # Changelog
 
-## 0.5.8
+## 0.5.9
 
+* Ensure query parameters are stringified
 * Allow URI construction to handle query parameter encoding
 
 ## 0.5.7
diff --git a/lib/src/generators/client.dart b/lib/src/generators/client.dart
index 950ac4d..4f8469f 100644
--- a/lib/src/generators/client.dart
+++ b/lib/src/generators/client.dart
@@ -243,6 +243,15 @@ class $clientName {
       );
     }
 
+    // Ensure query parameters are strings or iterable of strings
+    queryParams = queryParams.map((key, value) {
+      if (value is List) {
+        return MapEntry(key, value.map((v) => v.toString()));
+      } else {
+        return MapEntry(key, value.toString());
+      }
+    });
+
     // Build the request URI
     final secure = Uri.parse(host).scheme == 'https';
     Uri uri;
diff --git a/pubspec.yaml b/pubspec.yaml
index f95e873..25ea8c5 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,6 +1,6 @@
 name: openapi_spec
 description: OpenAPI Specification generator using native Dart code, as well as an all-in-one parser of existing specifications.
-version: 0.5.8
+version: 0.5.9
 maintainer: Taza Technology LLC
 repository: https://github.com/tazatechnology/openapi_spec
 issue_tracker: https://github.com/tazatechnology/openapi_spec/issues