diff --git a/crates/polars-ops/src/frame/join/hash_join/single_keys_inner.rs b/crates/polars-ops/src/frame/join/hash_join/single_keys_inner.rs
index a97431c67e12..da6bd64a3134 100644
--- a/crates/polars-ops/src/frame/join/hash_join/single_keys_inner.rs
+++ b/crates/polars-ops/src/frame/join/hash_join/single_keys_inner.rs
@@ -60,7 +60,7 @@ where
             .map(|v| v.clone().into_iter().size_hint().1.unwrap())
             .sum();
         if !join_nulls {
-            expected_size = expected_size - build_null_count;
+            expected_size -= build_null_count;
         }
         let hash_tbls = build_tables(build, join_nulls);
         let build_size = hash_tbls.iter().map(|m| m.len()).sum();
diff --git a/crates/polars-ops/src/frame/join/hash_join/single_keys_left.rs b/crates/polars-ops/src/frame/join/hash_join/single_keys_left.rs
index 0367770701e2..b23d9de1776f 100644
--- a/crates/polars-ops/src/frame/join/hash_join/single_keys_left.rs
+++ b/crates/polars-ops/src/frame/join/hash_join/single_keys_left.rs
@@ -127,7 +127,7 @@ where
     let hash_tbls = if validate.needs_checks() {
         let mut expected_size = build.iter().map(|v| v.size_hint().1.unwrap()).sum();
         if !join_nulls {
-            expected_size = expected_size - build_null_count;
+            expected_size -= build_null_count;
         }
         let hash_tbls = build_tables(build, join_nulls);
         let build_size = hash_tbls.iter().map(|m| m.len()).sum();