diff --git a/pkstrings/src/lib.rs b/pkstrings/src/lib.rs
index 2216e40..f1ee4e7 100644
--- a/pkstrings/src/lib.rs
+++ b/pkstrings/src/lib.rs
@@ -114,7 +114,8 @@ lazy_static! {
         }
         map
     };
-    static ref HEXTOSTR: HashMap<u8, char> = {
+
+    static ref HEXTOSTR: Vec<Option<char>> = {
         let tmp = [
             (0x80, 'A'),
             (0x81, 'B'),
@@ -202,11 +203,11 @@ lazy_static! {
             (0x50, '@'),
         ];
 
-        let mut map = HashMap::new();
+        let mut vec: Vec<Option<char>> = [None; 255].to_vec();
         for (k, v) in tmp.iter() {
-            map.insert(*k, *v);
+            vec[*k] = Some(*v);
         }
-        map
+        vec
     };
 }
 
@@ -240,8 +241,9 @@ impl TryFrom<&[u8]> for PKString {
         let placeholder = '_';
 
         for ord in data {
-            if let Some(chr) = HEXTOSTR.get(&ord) {
-                buf.push(*chr);
+            let ord = *ord as usize;
+            if let Some(chr) = HEXTOSTR[ord] {
+                buf.push(chr.clone());
             } else {
                 buf.push(placeholder);
             }