diff --git a/packages/opencode/src/provider/transform.ts b/packages/opencode/src/provider/transform.ts
index 6ca089c2f0..ccb9c5dfbc 100644
--- a/packages/opencode/src/provider/transform.ts
+++ b/packages/opencode/src/provider/transform.ts
@@ -82,7 +82,11 @@ export namespace ProviderTransform {
         return msg
       })
     }
-    if (model.providerID === "mistral" || model.api.id.toLowerCase().includes("mistral")) {
+    if (
+      model.providerID === "mistral" ||
+      model.api.id.toLowerCase().includes("mistral") ||
+      model.api.id.toLocaleLowerCase().includes("devstral")
+    ) {
       const result: ModelMessage[] = []
       for (let i = 0; i < msgs.length; i++) {
         const msg = msgs[i]