diff --git a/braintrust-java-core/src/main/kotlin/com/braintrustdata/api/core/ClientOptions.kt b/braintrust-java-core/src/main/kotlin/com/braintrustdata/api/core/ClientOptions.kt
index a63ea9ec..4700499e 100755
--- a/braintrust-java-core/src/main/kotlin/com/braintrustdata/api/core/ClientOptions.kt
+++ b/braintrust-java-core/src/main/kotlin/com/braintrustdata/api/core/ClientOptions.kt
@@ -108,6 +108,7 @@ private constructor(
             headers.put("X-Stainless-OS", getOsName())
             headers.put("X-Stainless-OS-Version", getOsVersion())
             headers.put("X-Stainless-Package-Version", getPackageVersion())
+            headers.put("X-Stainless-Runtime", "JRE")
             headers.put("X-Stainless-Runtime-Version", getJavaVersion())
             if (!apiKey.isNullOrEmpty()) {
                 headers.put("Authorization", "Bearer ${apiKey}")