diff --git a/ruma-identifiers/src/device_key_id.rs b/ruma-identifiers/src/device_key_id.rs
index 89f37033..8feafeeb 100644
--- a/ruma-identifiers/src/device_key_id.rs
+++ b/ruma-identifiers/src/device_key_id.rs
@@ -21,7 +21,7 @@ impl DeviceKeyId {
 
         let mut res = String::with_capacity(algorithm.len() + 1 + device_id.len());
         res.push_str(algorithm);
-        res.push_str(":");
+        res.push(':');
         res.push_str(device_id);
 
         let colon_idx =
diff --git a/ruma-identifiers/src/server_key_id.rs b/ruma-identifiers/src/server_key_id.rs
index ce7caf4a..ae8f5971 100644
--- a/ruma-identifiers/src/server_key_id.rs
+++ b/ruma-identifiers/src/server_key_id.rs
@@ -18,7 +18,7 @@ impl ServerKeyId {
 
         let mut res = String::with_capacity(algorithm.len() + 1 + version.len());
         res.push_str(algorithm);
-        res.push_str(":");
+        res.push(':');
         res.push_str(version);
 
         let colon_idx =