--- a/Cargo.toml
+++ b/Cargo.toml
@@ -70,3 +70,3 @@
     "dep:heapless",
-    "heapless/cas",
+    "heapless/portable-atomic",
 ]
@@ -89,7 +89,7 @@
 package = "embedded-io"
 
 [dependencies.heapless]
-version = "0.7.0"
+version = "0.8.0"
 features = ["serde"]
 optional = true
 default-features = false