diff --git a/src/sha1.rs b/src/sha1.rs
index 8e21c73..6e9d80e 100644
--- a/src/sha1.rs
+++ b/src/sha1.rs
@@ -137,6 +137,7 @@ impl crate::Hash for Hash {
     }
 }
 
+#[allow(clippy::many_single_char_names)]
 impl HashEngine {
     // Basic unoptimized algorithm from Wikipedia
     fn process_block(&mut self) {
diff --git a/src/sha256.rs b/src/sha256.rs
index d496962..2a36a3f 100644
--- a/src/sha256.rs
+++ b/src/sha256.rs
@@ -230,6 +230,7 @@ macro_rules! round(
     )
 );
 
+#[allow(clippy::many_single_char_names)]
 impl HashEngine {
     /// Create a new [HashEngine] from a midstate.
     ///
diff --git a/src/sha512.rs b/src/sha512.rs
index 444ca42..7c5c6bb 100644
--- a/src/sha512.rs
+++ b/src/sha512.rs
@@ -217,6 +217,7 @@ macro_rules! round(
     )
 );
 
+#[allow(clippy::many_single_char_names)]
 impl HashEngine {
     // Algorithm copied from libsecp256k1
     fn process_block(&mut self) {