diff --git a/src/eval/data_check.rs b/src/eval/data_check.rs
index 1e9e4a7f..2b031bcd 100644
--- a/src/eval/data_check.rs
+++ b/src/eval/data_check.rs
@@ -9,6 +9,60 @@ use std::borrow::Borrow;
 use std::prelude::v1::*;
 
 impl Dynamic {
+    /// Recursively calculate the sizes of an array.
+    ///
+    /// Sizes returned are `(` [`Array`][crate::Array], [`Map`][crate::Map] and [`String`] `)`.
+    ///
+    /// # Panics
+    ///
+    /// Panics if any interior data is shared (should never happen).
+    #[cfg(not(feature = "no_index"))]
+    #[inline]
+    pub(crate) fn calc_array_sizes(array: &crate::Array, _top: bool) -> (usize, usize, usize) {
+        array
+            .iter()
+            .fold((0, 0, 0), |(ax, mx, sx), value| match value.0 {
+                Union::Array(..) => {
+                    let (a, m, s) = value.calc_data_sizes(false);
+                    (ax + a + 1, mx + m, sx + s)
+                }
+                Union::Blob(ref a, ..) => (ax + 1 + a.len(), mx, sx),
+                #[cfg(not(feature = "no_object"))]
+                Union::Map(..) => {
+                    let (a, m, s) = value.calc_data_sizes(false);
+                    (ax + a + 1, mx + m, sx + s)
+                }
+                Union::Str(ref s, ..) => (ax + 1, mx, sx + s.len()),
+                _ => (ax + 1, mx, sx),
+            })
+    }
+    /// Recursively calculate the sizes of a map.
+    ///
+    /// Sizes returned are `(` [`Array`][crate::Array], [`Map`][crate::Map] and [`String`] `)`.
+    ///
+    /// # Panics
+    ///
+    /// Panics if any interior data is shared (should never happen).
+    #[cfg(not(feature = "no_object"))]
+    #[inline]
+    pub(crate) fn calc_map_sizes(map: &crate::Map, _top: bool) -> (usize, usize, usize) {
+        map.values()
+            .fold((0, 0, 0), |(ax, mx, sx), value| match value.0 {
+                #[cfg(not(feature = "no_index"))]
+                Union::Array(..) => {
+                    let (a, m, s) = value.calc_data_sizes(false);
+                    (ax + a, mx + m + 1, sx + s)
+                }
+                #[cfg(not(feature = "no_index"))]
+                Union::Blob(ref a, ..) => (ax + a.len(), mx, sx),
+                Union::Map(..) => {
+                    let (a, m, s) = value.calc_data_sizes(false);
+                    (ax + a, mx + m + 1, sx + s)
+                }
+                Union::Str(ref s, ..) => (ax, mx + 1, sx + s.len()),
+                _ => (ax, mx + 1, sx),
+            })
+    }
     /// Recursively calculate the sizes of a value.
     ///
     /// Sizes returned are `(` [`Array`][crate::Array], [`Map`][crate::Map] and [`String`] `)`.
@@ -16,47 +70,15 @@ impl Dynamic {
     /// # Panics
     ///
     /// Panics if any interior data is shared (should never happen).
+    #[inline]
     pub(crate) fn calc_data_sizes(&self, _top: bool) -> (usize, usize, usize) {
         match self.0 {
             #[cfg(not(feature = "no_index"))]
-            Union::Array(ref arr, ..) => {
-                arr.iter()
-                    .fold((0, 0, 0), |(ax, mx, sx), value| match value.0 {
-                        Union::Array(..) => {
-                            let (a, m, s) = value.calc_data_sizes(false);
-                            (ax + a + 1, mx + m, sx + s)
-                        }
-                        Union::Blob(ref a, ..) => (ax + 1 + a.len(), mx, sx),
-                        #[cfg(not(feature = "no_object"))]
-                        Union::Map(..) => {
-                            let (a, m, s) = value.calc_data_sizes(false);
-                            (ax + a + 1, mx + m, sx + s)
-                        }
-                        Union::Str(ref s, ..) => (ax + 1, mx, sx + s.len()),
-                        _ => (ax + 1, mx, sx),
-                    })
-            }
+            Union::Array(ref arr, ..) => Self::calc_array_sizes(&**arr, _top),
             #[cfg(not(feature = "no_index"))]
             Union::Blob(ref blob, ..) => (blob.len(), 0, 0),
             #[cfg(not(feature = "no_object"))]
-            Union::Map(ref map, ..) => {
-                map.values()
-                    .fold((0, 0, 0), |(ax, mx, sx), value| match value.0 {
-                        #[cfg(not(feature = "no_index"))]
-                        Union::Array(..) => {
-                            let (a, m, s) = value.calc_data_sizes(false);
-                            (ax + a, mx + m + 1, sx + s)
-                        }
-                        #[cfg(not(feature = "no_index"))]
-                        Union::Blob(ref a, ..) => (ax + a.len(), mx, sx),
-                        Union::Map(..) => {
-                            let (a, m, s) = value.calc_data_sizes(false);
-                            (ax + a, mx + m + 1, sx + s)
-                        }
-                        Union::Str(ref s, ..) => (ax, mx + 1, sx + s.len()),
-                        _ => (ax, mx + 1, sx),
-                    })
-            }
+            Union::Map(ref map, ..) => Self::calc_map_sizes(&**map, _top),
             Union::Str(ref s, ..) => (0, 0, s.len()),
             #[cfg(not(feature = "no_closure"))]
             Union::Shared(..) if _top => self.read_lock::<Self>().unwrap().calc_data_sizes(true),
diff --git a/src/packages/array_basic.rs b/src/packages/array_basic.rs
index c1502d4a..b8396991 100644
--- a/src/packages/array_basic.rs
+++ b/src/packages/array_basic.rs
@@ -235,52 +235,15 @@ pub mod array_functions {
 
         // Check if array will be over max size limit
         #[cfg(not(feature = "unchecked"))]
-        {
-            use crate::types::dynamic::Union;
+        if _ctx.engine().max_array_size() > 0 {
+            let pad = len - array.len();
+            let (a, m, s) = Dynamic::calc_array_sizes(array, true);
+            let (ax, mx, sx) = item.calc_data_sizes(true);
 
-            if _ctx.engine().max_array_size() > 0 && len > _ctx.engine().max_array_size() {
-                return Err(
-                    ERR::ErrorDataTooLarge("Size of array".to_string(), Position::NONE).into(),
-                );
-            }
-
-            let check_sizes = match item.0 {
-                Union::Str(..) => true,
-                Union::Array(..) => true,
-                #[cfg(not(feature = "no_object"))]
-                Union::Map(..) => true,
-                _ => false,
-            };
-
-            if check_sizes {
-                let mut arr_len = array.len();
-                let mut arr = Dynamic::from_array(mem::take(array));
-
-                let (mut a1, mut m1, mut s1) = arr.calc_data_sizes(true);
-                let (a2, m2, s2) = item.calc_data_sizes(true);
-
-                {
-                    let mut guard = arr.write_lock::<Array>().unwrap();
-
-                    while arr_len < len {
-                        a1 += a2;
-                        m1 += m2;
-                        s1 += s2;
-
-                        _ctx.engine().throw_on_size((a1, m1, s1))?;
-
-                        guard.push(item.clone());
-                        arr_len += 1;
-                    }
-                }
-
-                *array = arr.into_array().unwrap();
-            } else {
-                array.resize(len, item);
-            }
+            _ctx.engine()
+                .throw_on_size((a + pad + ax * pad, m + mx * pad, s + sx * pad))?;
         }
 
-        #[cfg(feature = "unchecked")]
         array.resize(len, item);
 
         Ok(())