diff --git a/src/Mappings/ElderFutharkMapping.cs b/src/Mappings/ElderFutharkMapping.cs
index 4619e49..0a643a3 100644
--- a/src/Mappings/ElderFutharkMapping.cs
+++ b/src/Mappings/ElderFutharkMapping.cs
@@ -3,11 +3,10 @@
 
 namespace Riimut.Mappings
 {
-    public class ElderFutharkMapping
+    internal class ElderFutharkMapping
     {
-        public static Dictionary<string, string> GetLettersToRunesDictionary()
-        {
-            return new Dictionary<string, string>()
+
+        private readonly static Dictionary<string, string> LettersToRunesMapping = new Dictionary<string, string>()
             {
                 {"a", "ᚨ"},
                 {"á", "ᚨ"},
@@ -52,11 +51,8 @@ public static Dictionary<string, string> GetLettersToRunesDictionary()
                 {"þ", "ᚦ"},
                 {" ", ":"},
             };
-        }
 
-        public static Dictionary<string, string> GetRunesToLettersDictionary()
-        {
-            return new Dictionary<string, string>()
+        private readonly static Dictionary<string, string> RunesToLettersMapping = new Dictionary<string, string>()
             {
                 {"ᚠ", "f"},
                 {"ᚢ", "u"},
@@ -87,6 +83,14 @@ public static Dictionary<string, string> GetRunesToLettersDictionary()
                 {"ᛞ", "d"},
                 {":", " "},
             };
+        public static Dictionary<string, string> GetLettersToRunesDictionary()
+        {
+            return LettersToRunesMapping;
+        }
+
+        public static Dictionary<string, string> GetRunesToLettersDictionary()
+        {
+            return RunesToLettersMapping;
         }
     }
 }
diff --git a/src/Mappings/FuthorcMapping.cs b/src/Mappings/FuthorcMapping.cs
index 9f04df9..bcf9a79 100644
--- a/src/Mappings/FuthorcMapping.cs
+++ b/src/Mappings/FuthorcMapping.cs
@@ -3,11 +3,9 @@
 
 namespace Riimut.Mappings
 {
-    public class FuthorcMapping
+    internal class FuthorcMapping
     {
-        public static Dictionary<string, string> GetLettersToRunesDictionary()
-        {
-            return new Dictionary<string, string>()
+        private readonly static Dictionary<string, string> LettersToRunesMapping = new Dictionary<string, string>()
             {
                 {"a", "ᚪ"},
                 {"á", "ᚪ"},
@@ -55,11 +53,8 @@ public static Dictionary<string, string> GetLettersToRunesDictionary()
                 {"þ", "ᚦ"},
                 {" ", ":"},
             };
-        }
 
-        public static Dictionary<string, string> GetRunesToLettersDictionary()
-        {
-            return new Dictionary<string, string>()
+        private readonly static Dictionary<string, string> RunesToLettersMapping = new Dictionary<string, string>()
             {
                 {"ᚠ", "f"},
                 {"ᚢ", "u"},
@@ -93,6 +88,15 @@ public static Dictionary<string, string> GetRunesToLettersDictionary()
                 {":", " "},
                 {"ᛠ", "ea"},
             };
+
+        public static Dictionary<string, string> GetLettersToRunesDictionary()
+        {
+            return LettersToRunesMapping;
+        }
+
+        public static Dictionary<string, string> GetRunesToLettersDictionary()
+        {
+            return RunesToLettersMapping;
         }
     }
 }
diff --git a/src/Mappings/MedievalFuthorkMapping.cs b/src/Mappings/MedievalFuthorkMapping.cs
index 17fabc4..68af35f 100644
--- a/src/Mappings/MedievalFuthorkMapping.cs
+++ b/src/Mappings/MedievalFuthorkMapping.cs
@@ -3,11 +3,9 @@
 
 namespace Riimut.Mappings
 {
-    public class MedievalFuthorkMapping
+    internal class MedievalFuthorkMapping
     {
-        public static Dictionary<string, string> GetLettersToRunesDictionary()
-        {
-            return new Dictionary<string, string>()
+        private readonly static Dictionary<string, string> LettersToRunesMapping = new Dictionary<string, string>()
             {
                 {"a", "ᛆ"},
                 {"á", "ᛆ"},
@@ -53,11 +51,8 @@ public static Dictionary<string, string> GetLettersToRunesDictionary()
                 {"þ", "ᚦ"},
                 {" ", ":"},
             };
-        }
 
-        public static Dictionary<string, string> GetRunesToLettersDictionary()
-        {
-            return new Dictionary<string, string>()
+        private readonly static Dictionary<string, string> RunesToLettersMapping = new Dictionary<string, string>()
             {
                 {"ᚠ", "f"},
                 {"ᚢ", "u"},
@@ -87,6 +82,14 @@ public static Dictionary<string, string> GetRunesToLettersDictionary()
                 {"ᚽ", "e"},
                 {"ᚵ", "g"},
             };
+        public static Dictionary<string, string> GetLettersToRunesDictionary()
+        {
+            return LettersToRunesMapping;
+        }
+
+        public static Dictionary<string, string> GetRunesToLettersDictionary()
+        {
+            return RunesToLettersMapping;
         }
     }
 }
diff --git a/src/Mappings/YoungerFutharkMapping.cs b/src/Mappings/YoungerFutharkMapping.cs
index abfd7d2..476c5b0 100644
--- a/src/Mappings/YoungerFutharkMapping.cs
+++ b/src/Mappings/YoungerFutharkMapping.cs
@@ -3,11 +3,9 @@
 
 namespace Riimut.Mappings
 {
-    public class YoungerFutharkMapping
+    internal class YoungerFutharkMapping
     {
-        public static Dictionary<string, string> GetLettersToRunesDictionary()
-        {
-            return new Dictionary<string, string>()
+        private readonly static Dictionary<string, string> LettersToRunesMapping = new Dictionary<string, string>()
             {
                 {"a", "ᛅ"},
                 {"á", "ᛅ"},
@@ -51,11 +49,8 @@ public static Dictionary<string, string> GetLettersToRunesDictionary()
                 {"ǫ", "ᚢ"},
                 {" ", ":"},
             };
-        }
 
-        public static Dictionary<string, string> GetRunesToLettersDictionary()
-        {
-            return new Dictionary<string, string>()
+        private readonly static Dictionary<string, string> RunesToLettersMapping = new Dictionary<string, string>()
             {
                 {"ᚠ", "f"},
                 {"ᚢ", "u"},
@@ -80,6 +75,14 @@ public static Dictionary<string, string> GetRunesToLettersDictionary()
                 {"ᛦ", "R"},
                 {":", " "},
             };
+        public static Dictionary<string, string> GetLettersToRunesDictionary()
+        {
+            return LettersToRunesMapping;
+        }
+
+        public static Dictionary<string, string> GetRunesToLettersDictionary()
+        {
+            return RunesToLettersMapping;
         }
     }
 }
diff --git a/src/Transform.cs b/src/Transform.cs
index ba88556..0d2eafa 100644
--- a/src/Transform.cs
+++ b/src/Transform.cs
@@ -12,11 +12,15 @@ public static string WithDictionary(string content, Dictionary<string, string> d
         {
             StringBuilder result = new StringBuilder();
 
-            foreach (char letter in content) {
+            foreach (char letter in content)
+            {
                 string part = Char.ToLower(letter).ToString();
-                if (dictionary.ContainsKey(part)) {
+                if (dictionary.ContainsKey(part))
+                {
                     result.Append(dictionary[part]);
-                } else {
+                }
+                else
+                {
                     result.Append(part);
                 }
             }
diff --git a/tests/YoungerFutharkTest.cs b/tests/YoungerFutharkTest.cs
index 6e12170..1c0212d 100644
--- a/tests/YoungerFutharkTest.cs
+++ b/tests/YoungerFutharkTest.cs
@@ -33,7 +33,7 @@ public void Transforms_Text_Content_To_Younger_Futhark()
         public void Transforms_Runes_To_Letters()
         {
             string runes = "ᚠᚢᚦᚬᚱᚴᚼᚽᚾᚿᛁᛅᛆᛋᛌᛏᛐᛒᛘᛚᛦ:";
-            string letters ="fuþorkhhnniaassttbmlR ";
+            string letters = "fuþorkhhnniaassttbmlR ";
 
             string result = YoungerFuthark.RunesToLetters(runes);
 
@@ -45,7 +45,7 @@ public void Transforms_Rune_Content_To_Latin_Letters()
         {
             // From Old Groms runestone.
             string runes = "ᛅᚢᚴ:ᛏᛅᚾᛁ:ᚴᛅᚱᚦᛁ:ᚴᚱᛁᛋᛏᚾᛅ";
-            string letters ="auk tani karþi kristna";
+            string letters = "auk tani karþi kristna";
 
             string result = YoungerFuthark.RunesToLetters(runes);