diff --git a/src/precompiles/blake2.rs b/src/precompiles/blake2.rs
index 47797ccaf..dffd19e3d 100644
--- a/src/precompiles/blake2.rs
+++ b/src/precompiles/blake2.rs
@@ -226,28 +226,28 @@ mod tests {
         assert!(matches!(
             test_blake2f_empty(),
             Err(ExitError::Other(Borrowed(
-                "input length invalid, must be 213 bytes"
+                "ERR_BLAKE2F_INVALID_LEN"
             )))
         ));
 
         assert!(matches!(
             test_blake2f_invalid_len_1(),
             Err(ExitError::Other(Borrowed(
-                "input length invalid, must be 213 bytes"
+                "ERR_BLAKE2F_INVALID_LEN"
             )))
         ));
 
         assert!(matches!(
             test_blake2f_invalid_len_2(),
             Err(ExitError::Other(Borrowed(
-                "input length invalid, must be 213 bytes"
+                "ERR_BLAKE2F_INVALID_LEN"
             )))
         ));
 
         assert!(matches!(
             test_blake2f_invalid_flag(),
             Err(ExitError::Other(Borrowed(
-                "incorrect final block indicator flag",
+                "ERR_BLAKE2F_FINAL_FLAG",
             )))
         ));
 
diff --git a/src/precompiles/bn128.rs b/src/precompiles/bn128.rs
index a42ccaf25..83f703288 100644
--- a/src/precompiles/bn128.rs
+++ b/src/precompiles/bn128.rs
@@ -421,7 +421,7 @@ mod tests {
         let res = BN128Add::<Byzantium>::run(&input, 500, &new_context());
         assert!(matches!(
             res,
-            Err(ExitError::Other(Borrowed("invalid curve point")))
+            Err(ExitError::Other(Borrowed("ERR_BN128_INVALID_POINT")))
         ));
     }
 
@@ -503,7 +503,7 @@ mod tests {
         let res = BN128Mul::<Byzantium>::run(&input, 40_000, &new_context());
         assert!(matches!(
             res,
-            Err(ExitError::Other(Borrowed("invalid curve point")))
+            Err(ExitError::Other(Borrowed("ERR_BN128_INVALID_POINT")))
         ));
     }
 
@@ -580,9 +580,7 @@ mod tests {
         let res = BN128Pair::<Byzantium>::run(&input, 260_000, &new_context());
         assert!(matches!(
             res,
-            Err(ExitError::Other(Borrowed(
-                "invalid `a` argument, not on curve"
-            )))
+            Err(ExitError::Other(Borrowed("ERR_BN128_INVALID_A")))
         ));
 
         // invalid input length
@@ -598,9 +596,7 @@ mod tests {
         let res = BN128Pair::<Byzantium>::run(&input, 260_000, &new_context());
         assert!(matches!(
             res,
-            Err(ExitError::Other(Borrowed(
-                "input length invalid, must be multiple of 192",
-            )))
+            Err(ExitError::Other(Borrowed("ERR_BN128_INVALID_LEN",)))
         ));
     }
 }
diff --git a/src/prelude.rs b/src/prelude.rs
index e2c36df92..a81da0d5d 100644
--- a/src/prelude.rs
+++ b/src/prelude.rs
@@ -15,8 +15,7 @@ pub use core::{convert::TryInto, marker::PhantomData, mem};
 #[cfg(feature = "std")]
 pub use std::{
     borrow::Cow::Borrowed, borrow::ToOwned, boxed::Box, collections::HashMap, convert::TryInto,
-    error::Error, fmt, marker::PhantomData, mem, string::String, string::ToString, vec,
-    vec::Vec,
+    error::Error, fmt, marker::PhantomData, mem, string::String, string::ToString, vec, vec::Vec,
 };
 
 pub use primitive_types::{H160, H256, U256};