diff --git a/packages/smithy-http/pyproject.toml b/packages/smithy-http/pyproject.toml
index 88de0861d..c63890900 100644
--- a/packages/smithy-http/pyproject.toml
+++ b/packages/smithy-http/pyproject.toml
@@ -13,7 +13,8 @@ awscrt = [
     "awscrt>=0.23.10",
 ]
 aiohttp = [
-    "aiohttp>=3.11.12",
+    "aiohttp>=3.11.12, <4.0",
+    "yarl"
 ]
 
 [build-system]