diff --git a/acvm-repo/acvm/src/pwg/blackbox/hash.rs b/acvm-repo/acvm/src/pwg/blackbox/hash.rs
index 1bc26f06188..24c835a636a 100644
--- a/acvm-repo/acvm/src/pwg/blackbox/hash.rs
+++ b/acvm-repo/acvm/src/pwg/blackbox/hash.rs
@@ -143,12 +143,22 @@ pub(crate) fn solve_poseidon2_permutation_opcode(
         return Err(OpcodeResolutionError::BlackBoxFunctionFailed(
             acir::BlackBoxFunc::Poseidon2Permutation,
             format!(
-                "the number of inputs does not match specified length. {} > {}",
+                "the number of inputs does not match specified length. {} != {}",
                 inputs.len(),
                 len
             ),
         ));
     }
+    if len as usize != outputs.len() {
+        return Err(OpcodeResolutionError::BlackBoxFunctionFailed(
+            acir::BlackBoxFunc::Poseidon2Permutation,
+            format!(
+                "the number of outputs does not match specified length. {} != {}",
+                outputs.len(),
+                len
+            ),
+        ));
+    }
 
     // Read witness assignments
     let mut state = Vec::new();
diff --git a/noir_stdlib/src/hash/poseidon2.nr b/noir_stdlib/src/hash/poseidon2.nr
index 64c1876b4e2..40eea029e82 100644
--- a/noir_stdlib/src/hash/poseidon2.nr
+++ b/noir_stdlib/src/hash/poseidon2.nr
@@ -93,7 +93,8 @@ impl Poseidon2 {
     }
 
     fn hash_internal<N>(input: [Field; N], in_len: u32, is_variable_length: bool) -> Field {
-        let iv : Field = (in_len as Field) * 18446744073709551616;
+        let two_pow_64 = 18446744073709551616;
+        let iv : Field = (in_len as Field) * two_pow_64;
         let mut sponge = Poseidon2::new(iv);
         for i in 0..input.len() {
             if i as u32 < in_len {