diff --git a/program-libs/zero-copy/src/slice_mut.rs b/program-libs/zero-copy/src/slice_mut.rs
index 1a5c5c3d8..c36bba58a 100644
--- a/program-libs/zero-copy/src/slice_mut.rs
+++ b/program-libs/zero-copy/src/slice_mut.rs
@@ -168,7 +168,7 @@ where
         }
 
         unsafe {
-            std::ptr::copy_nonoverlapping(slice.as_ptr(), self.data_as_mut_ptr(), slice.len());
+            std::ptr::copy_nonoverlapping(slice.as_ptr(), self.data_as_mut_ptr(), len);
         }
     }
 }
diff --git a/program-libs/zero-copy/src/vec.rs b/program-libs/zero-copy/src/vec.rs
index 9f2040c60..3229e203b 100644
--- a/program-libs/zero-copy/src/vec.rs
+++ b/program-libs/zero-copy/src/vec.rs
@@ -199,7 +199,7 @@ where
         &mut self.data.as_mut_slice()[..len]
     }
 
-    pub fn copy_from_slice(&mut self, slice: &[T]) {
+    pub fn extend_from_slice(&mut self, slice: &[T]) {
         let len = self.len();
         let new_len = len + slice.len();
         if new_len > self.capacity() {
diff --git a/program-libs/zero-copy/tests/vec_tests.rs b/program-libs/zero-copy/tests/vec_tests.rs
index 617e49b44..c20f6a1cd 100644
--- a/program-libs/zero-copy/tests/vec_tests.rs
+++ b/program-libs/zero-copy/tests/vec_tests.rs
@@ -376,7 +376,7 @@ fn test_zero_copy_vec_to_array() {
     let capacity = 16;
     let mut data = vec![0; ZeroCopyVecUsize::<u32>::required_size_for_capacity(capacity)];
     let mut vec = ZeroCopyVecUsize::<u32>::new(capacity, &mut data).unwrap();
-    vec.copy_from_slice(&[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]);
+    vec.extend_from_slice(&[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]);
 
     let arr: [u32; 16] = vec.try_into_array().unwrap();
     assert_eq!(arr, [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]);