diff --git a/src/core.ts b/src/core.ts
index dfe9bd5..dac4897 100644
--- a/src/core.ts
+++ b/src/core.ts
@@ -818,7 +818,8 @@ const getPlatformProperties = (): PlatformProperties => {
       'X-Stainless-OS': normalizePlatform(Deno.build.os),
       'X-Stainless-Arch': normalizeArch(Deno.build.arch),
       'X-Stainless-Runtime': 'deno',
-      'X-Stainless-Runtime-Version': Deno.version,
+      'X-Stainless-Runtime-Version':
+        typeof Deno.version === 'string' ? Deno.version : Deno.version?.deno ?? 'unknown',
     };
   }
   if (typeof EdgeRuntime !== 'undefined') {