diff --git a/src/bitmap/store/array_store/mod.rs b/src/bitmap/store/array_store/mod.rs
index 32ec08da..c8747075 100644
--- a/src/bitmap/store/array_store/mod.rs
+++ b/src/bitmap/store/array_store/mod.rs
@@ -7,7 +7,7 @@ use std::cmp::Ordering;
 use std::cmp::Ordering::*;
 use std::convert::{TryFrom, TryInto};
 use std::fmt::{Display, Formatter};
-use std::ops::{BitAnd, BitAndAssign, BitOr, BitXor, BitXorAssign, RangeInclusive, Sub, SubAssign};
+use std::ops::{BitAnd, BitAndAssign, BitOr, BitXor, RangeInclusive, Sub, SubAssign};
 
 use super::bitmap_store::{bit, key, BitmapStore, BITMAP_LENGTH};
 
@@ -368,44 +368,6 @@ impl BitXor<Self> for &ArrayStore {
     }
 }
 
-impl BitXorAssign<&Self> for ArrayStore {
-    fn bitxor_assign(&mut self, rhs: &Self) {
-        #[cfg(feature = "simd")]
-        {
-            let mut visitor = VecWriter::new(self.vec.len().min(rhs.vec.len()));
-            vector::xor(self.as_slice(), rhs.as_slice(), &mut visitor);
-            self.vec = visitor.into_inner()
-        }
-        #[cfg(not(feature = "simd"))]
-        {
-            let mut i1 = 0usize;
-            let mut iter2 = rhs.vec.iter();
-            let mut current2 = iter2.next();
-            while i1 < self.vec.len() {
-                match current2.map(|c2| self.vec[i1].cmp(c2)) {
-                    None => break,
-                    Some(Less) => {
-                        i1 += 1;
-                    }
-                    Some(Greater) => {
-                        self.vec.insert(i1, *current2.unwrap());
-                        i1 += 1;
-                        current2 = iter2.next();
-                    }
-                    Some(Equal) => {
-                        self.vec.remove(i1);
-                        current2 = iter2.next();
-                    }
-                }
-            }
-            if let Some(current) = current2 {
-                self.vec.push(*current);
-                self.vec.extend(iter2.cloned());
-            }
-        }
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
diff --git a/src/bitmap/store/mod.rs b/src/bitmap/store/mod.rs
index 3534ef45..22e4b7a9 100644
--- a/src/bitmap/store/mod.rs
+++ b/src/bitmap/store/mod.rs
@@ -365,13 +365,12 @@ impl BitXor<&Store> for &Store {
 
 impl BitXorAssign<Store> for Store {
     fn bitxor_assign(&mut self, mut rhs: Store) {
-        // TODO improve this function
         match (self, &mut rhs) {
-            (&mut Array(ref mut vec1), &mut Array(ref mut vec2)) => {
-                BitXorAssign::bitxor_assign(vec1, vec2);
+            (&mut Array(ref mut vec1), &mut Array(ref vec2)) => {
+                *vec1 = BitXor::bitxor(&*vec1, vec2);
             }
-            (&mut Bitmap(ref mut bits1), &mut Array(ref mut vec2)) => {
-                BitXorAssign::bitxor_assign(bits1, &*vec2);
+            (&mut Bitmap(ref mut bits1), &mut Array(ref vec2)) => {
+                BitXorAssign::bitxor_assign(bits1, vec2);
             }
             (&mut Bitmap(ref mut bits1), &mut Bitmap(ref bits2)) => {
                 BitXorAssign::bitxor_assign(bits1, bits2);
@@ -388,7 +387,8 @@ impl BitXorAssign<&Store> for Store {
     fn bitxor_assign(&mut self, rhs: &Store) {
         match (self, rhs) {
             (&mut Array(ref mut vec1), &Array(ref vec2)) => {
-                BitXorAssign::bitxor_assign(vec1, vec2);
+                let this = mem::take(vec1);
+                *vec1 = BitXor::bitxor(&this, vec2);
             }
             (&mut Bitmap(ref mut bits1), &Array(ref vec2)) => {
                 BitXorAssign::bitxor_assign(bits1, vec2);
@@ -396,10 +396,10 @@ impl BitXorAssign<&Store> for Store {
             (&mut Bitmap(ref mut bits1), &Bitmap(ref bits2)) => {
                 BitXorAssign::bitxor_assign(bits1, bits2);
             }
-            (this @ &mut Array(..), &Bitmap(..)) => {
-                let mut new = rhs.clone();
-                BitXorAssign::bitxor_assign(&mut new, &*this);
-                *this = new;
+            (this @ &mut Array(..), &Bitmap(ref bits2)) => {
+                let mut lhs: Store = Bitmap(bits2.clone());
+                BitXorAssign::bitxor_assign(&mut lhs, &*this);
+                *this = lhs;
             }
         }
     }