diff --git a/sha3/tests/turboshake.rs b/sha3/tests/turboshake.rs
index 42881c688..3d17ce38a 100644
--- a/sha3/tests/turboshake.rs
+++ b/sha3/tests/turboshake.rs
@@ -4,13 +4,15 @@ use digest::ExtendableOutput;
 pub(crate) fn turbo_shake_test<D, F>(
     input: &[u8],
     output: &[u8],
-    truncate_output: usize,
+    truncate_output: u64,
     new: F,
 ) -> Option<&'static str>
 where
     D: ExtendableOutput + Debug + Clone,
     F: Fn() -> D,
 {
+    let truncate_output: usize = truncate_output.try_into().unwrap();
+
     let mut hasher = new();
     let mut buf = [0u8; 16 * 1024];
     let buf = &mut buf[..truncate_output + output.len()];
@@ -55,7 +57,7 @@ macro_rules! new_turbo_shake_test {
                     input.to_vec()
                 } else if (input.len() == 0) {
                     let pattern_length =
-                        usize::from_be_bytes(input_pattern_length.try_into().unwrap());
+                        u64::from_be_bytes(input_pattern_length.try_into().unwrap());
                     let mut input = Vec::<u8>::new();
                     for value in 0..pattern_length {
                         input.push((value % 0xFB).try_into().unwrap());
@@ -74,7 +76,7 @@ macro_rules! new_turbo_shake_test {
                 if let Some(desc) = $test_func(
                     &input,
                     output,
-                    usize::from_be_bytes(truncate_output.try_into().unwrap()),
+                    u64::from_be_bytes(truncate_output.try_into().unwrap()),
                     || <$hasher>::from_core(<$hasher_core>::new(domain_separation[0])),
                 ) {
                     panic!(