diff --git a/Cargo.toml b/Cargo.toml
index d8d1d23f..c8afd181 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -24,7 +24,7 @@ default-features = false
 version = "1.0.100"
 
 [dependencies.defmt]
-version = "0.3.0"
+version = "0.3.5"
 default-features = false
 optional = true
 
diff --git a/src/de/mod.rs b/src/de/mod.rs
index c04d7379..613323bc 100644
--- a/src/de/mod.rs
+++ b/src/de/mod.rs
@@ -75,7 +75,9 @@ pub enum Error {
 
     /// Error with a custom message that was preserved.
     #[cfg(feature = "custom-error-messages")]
-    CustomErrorWithMessage(heapless::String<64>),
+    CustomErrorWithMessage(
+        #[cfg_attr(feature = "defmt", defmt(Debug2Format))] heapless::String<64>,
+    ),
 }
 
 impl serde::de::StdError for Error {}