diff --git a/rtic-sync/Cargo.toml b/rtic-sync/Cargo.toml
index ce0014c581c..0cb5a1060ed 100644
--- a/rtic-sync/Cargo.toml
+++ b/rtic-sync/Cargo.toml
@@ -18,7 +18,7 @@ repository = "https://github.com/rtic-rs/rtic"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-heapless = "0.8"
+heapless = "0.9"
 critical-section = "1"
 rtic-common = { version = "1.0.0", path = "../rtic-common" }
 portable-atomic = { version = "1", default-features = false }