diff --git a/hashes/src/ripemd160.rs b/hashes/src/ripemd160.rs
index 30d24172..4b750978 100644
--- a/hashes/src/ripemd160.rs
+++ b/hashes/src/ripemd160.rs
@@ -469,7 +469,7 @@ mod tests {
 
         for test in tests {
             // Hash through high-level API, check hex encoding/decoding
-            let hash = ripemd160::Hash::hash(&test.input.as_bytes());
+            let hash = ripemd160::Hash::hash(test.input.as_bytes());
             assert_eq!(hash, ripemd160::Hash::from_hex(test.output_str).expect("parse hex"));
             assert_eq!(&hash[..], &test.output[..]);
             assert_eq!(&hash.to_hex(), &test.output_str);
diff --git a/hashes/src/sha1.rs b/hashes/src/sha1.rs
index a342d193..f5cae9a2 100644
--- a/hashes/src/sha1.rs
+++ b/hashes/src/sha1.rs
@@ -195,7 +195,7 @@ mod tests {
 
         for test in tests {
             // Hash through high-level API, check hex encoding/decoding
-            let hash = sha1::Hash::hash(&test.input.as_bytes());
+            let hash = sha1::Hash::hash(test.input.as_bytes());
             assert_eq!(hash, sha1::Hash::from_hex(test.output_str).expect("parse hex"));
             assert_eq!(&hash[..], &test.output[..]);
             assert_eq!(&hash.to_hex(), &test.output_str);
diff --git a/hashes/src/sha256.rs b/hashes/src/sha256.rs
index cc4d5364..b6336fa6 100644
--- a/hashes/src/sha256.rs
+++ b/hashes/src/sha256.rs
@@ -371,7 +371,7 @@ mod tests {
 
         for test in tests {
             // Hash through high-level API, check hex encoding/decoding
-            let hash = sha256::Hash::hash(&test.input.as_bytes());
+            let hash = sha256::Hash::hash(test.input.as_bytes());
             assert_eq!(hash, sha256::Hash::from_hex(test.output_str).expect("parse hex"));
             assert_eq!(&hash[..], &test.output[..]);
             assert_eq!(&hash.to_hex(), &test.output_str);
diff --git a/hashes/src/sha256d.rs b/hashes/src/sha256d.rs
index 6ecccdc4..1a3e75b3 100644
--- a/hashes/src/sha256d.rs
+++ b/hashes/src/sha256d.rs
@@ -74,7 +74,7 @@ mod tests {
 
         for test in tests {
             // Hash through high-level API, check hex encoding/decoding
-            let hash = sha256d::Hash::hash(&test.input.as_bytes());
+            let hash = sha256d::Hash::hash(test.input.as_bytes());
             assert_eq!(hash, sha256d::Hash::from_hex(test.output_str).expect("parse hex"));
             assert_eq!(&hash[..], &test.output[..]);
             assert_eq!(&hash.to_hex(), &test.output_str);
diff --git a/hashes/src/sha512.rs b/hashes/src/sha512.rs
index 3298d4a6..876614a0 100644
--- a/hashes/src/sha512.rs
+++ b/hashes/src/sha512.rs
@@ -368,7 +368,7 @@ mod tests {
 
         for test in tests {
             // Hash through high-level API, check hex encoding/decoding
-            let hash = sha512::Hash::hash(&test.input.as_bytes());
+            let hash = sha512::Hash::hash(test.input.as_bytes());
             assert_eq!(hash, sha512::Hash::from_hex(test.output_str).expect("parse hex"));
             assert_eq!(&hash[..], &test.output[..]);
             assert_eq!(&hash.to_hex(), &test.output_str);