diff --git a/benches/benchs.rs b/benches/benchs.rs
index 5812051..f573002 100644
--- a/benches/benchs.rs
+++ b/benches/benchs.rs
@@ -9,9 +9,8 @@ extern crate test;
 use evalexpr::build_operator_tree;
 use rand::{distributions::Uniform, seq::SliceRandom, Rng, SeedableRng};
 use rand_pcg::Pcg32;
-use std::hint::black_box;
+use std::{fmt::Write, hint::black_box};
 use test::Bencher;
-use std::fmt::Write;
 
 const BENCHMARK_LEN: usize = 100_000;
 const EXPONENTIAL_TUPLE_ITERATIONS: usize = 12;
diff --git a/src/token/mod.rs b/src/token/mod.rs
index 0cde4e4..7b9d504 100644
--- a/src/token/mod.rs
+++ b/src/token/mod.rs
@@ -445,6 +445,7 @@ pub(crate) fn tokenize(string: &str) -> EvalexprResult<Vec<Token>> {
 #[cfg(test)]
 mod tests {
     use crate::token::{char_to_partial_token, tokenize};
+    use std::fmt::Write;
 
     #[test]
     fn test_partial_token_display() {
@@ -468,7 +469,7 @@ mod tests {
         let mut result_string = String::new();
 
         for token in tokens {
-            result_string += &format!("{} ", token);
+            write!(result_string, "{} ", token).unwrap();
         }
 
         assert_eq!(token_string, result_string);