diff --git a/src/main/java/uk/org/okapibarcode/backend/ChannelCode.java b/src/main/java/uk/org/okapibarcode/backend/ChannelCode.java
index a2dbd6f8..ef4f27dc 100644
--- a/src/main/java/uk/org/okapibarcode/backend/ChannelCode.java
+++ b/src/main/java/uk/org/okapibarcode/backend/ChannelCode.java
@@ -28,8 +28,8 @@ public class ChannelCode extends Symbol {
 
     private int[] space = new int[11];
     private int[] bar = new int[11];
-    private double currentValue;
-    private double targetValue;
+    private int currentValue;
+    private int targetValue;
 
     /**
      * Sets the preferred number of channels used to encode data. This setting will be
@@ -39,7 +39,7 @@ public class ChannelCode extends Symbol {
      */
     public void setPreferredNumberOfChannels(int channels) {
         if (channels < 3 || channels > 8) {
-            throw new IllegalArgumentException("Invalid Channel Code number of channels: " + channels);
+            throw new IllegalArgumentException("Invalid number of channels: " + channels);
         }
         preferredNumberOfChannels = channels;
     }
@@ -56,26 +56,16 @@ public int getPreferredNumberOfChannels() {
     @Override
     protected void encode() {
 
-        int channels;
-        int i;
-        int leadingZeroCount;
-
         if (content.length() > 7) {
-            throw new OkapiException("Input too long");
+            throw new OkapiException("Input data too long");
         }
 
         if (!content.matches("[0-9]+")) {
-            throw new OkapiException("Invalid characters in input");
-        }
-
-        if (preferredNumberOfChannels <= 2 || preferredNumberOfChannels > 8) {
-            channels = 3;
-        } else {
-            channels = preferredNumberOfChannels;
+            throw new OkapiException("Invalid characters in data");
         }
 
+        int channels = preferredNumberOfChannels;
         targetValue = Integer.parseInt(content);
-
         switch (channels) {
             case 3:
                 if (targetValue > 26) {
@@ -109,7 +99,7 @@ protected void encode() {
 
         infoLine("Channels Used: " + channels);
 
-        for (i = 0; i < 11; i++) {
+        for (int i = 0; i < 11; i++) {
             bar[i] = 0;
             space[i] = 0;
         }
@@ -119,14 +109,14 @@ protected void encode() {
         pattern = new String[1];
         nextSpace(channels, 3, channels, channels);
 
-        leadingZeroCount = channels - 1 - content.length();
-
-        readable = "";
-        for (i = 0; i < leadingZeroCount; i++) {
-            readable += "0";
+        StringBuilder text = new StringBuilder();
+        int leadingZeroCount = channels - 1 - content.length();
+        for (int i = 0; i < leadingZeroCount; i++) {
+            text.append('0');
         }
-        readable += content;
+        text.append(content);
 
+        readable = text.toString();
         row_count = 1;
         row_height = new int[] { -1 };
     }
diff --git a/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-3-channels-to-4.png b/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-3-channels-to-4.png
new file mode 100644
index 00000000..6d2907dd
Binary files /dev/null and b/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-3-channels-to-4.png differ
diff --git a/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-3-channels-to-4.properties b/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-3-channels-to-4.properties
new file mode 100644
index 00000000..f9f445ad
--- /dev/null
+++ b/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-3-channels-to-4.properties
@@ -0,0 +1,12 @@
+PROPERTIES
+
+preferredNumberOfChannels=3
+content=27
+
+LOG
+
+Channels Used: 4
+
+CODEWORDS
+
+111100111111221212300000000
diff --git a/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-3-channels-to-8.png b/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-3-channels-to-8.png
new file mode 100644
index 00000000..e2138acb
Binary files /dev/null and b/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-3-channels-to-8.png differ
diff --git a/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-3-channels-to-8.properties b/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-3-channels-to-8.properties
new file mode 100644
index 00000000..a9511833
--- /dev/null
+++ b/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-3-channels-to-8.properties
@@ -0,0 +1,12 @@
+PROPERTIES
+
+preferredNumberOfChannels=3
+content=576689
+
+LOG
+
+Channels Used: 8
+
+CODEWORDS
+
+111100111111213211212213143
diff --git a/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-4-channels-to-5.png b/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-4-channels-to-5.png
new file mode 100644
index 00000000..46676093
Binary files /dev/null and b/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-4-channels-to-5.png differ
diff --git a/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-4-channels-to-5.properties b/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-4-channels-to-5.properties
new file mode 100644
index 00000000..7bd9fcce
--- /dev/null
+++ b/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-4-channels-to-5.properties
@@ -0,0 +1,12 @@
+PROPERTIES
+
+preferredNumberOfChannels=4
+content=293
+
+LOG
+
+Channels Used: 5
+
+CODEWORDS
+
+111100111111214311131000000
diff --git a/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-5-channels-to-6.png b/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-5-channels-to-6.png
new file mode 100644
index 00000000..7391ef71
Binary files /dev/null and b/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-5-channels-to-6.png differ
diff --git a/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-5-channels-to-6.properties b/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-5-channels-to-6.properties
new file mode 100644
index 00000000..b463fb9e
--- /dev/null
+++ b/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-5-channels-to-6.properties
@@ -0,0 +1,12 @@
+PROPERTIES
+
+preferredNumberOfChannels=5
+content=3494
+
+LOG
+
+Channels Used: 6
+
+CODEWORDS
+
+111100111111213411232110000
diff --git a/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-6-channels-to-7.png b/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-6-channels-to-7.png
new file mode 100644
index 00000000..5d528424
Binary files /dev/null and b/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-6-channels-to-7.png differ
diff --git a/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-6-channels-to-7.properties b/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-6-channels-to-7.properties
new file mode 100644
index 00000000..f30dc180
--- /dev/null
+++ b/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-6-channels-to-7.properties
@@ -0,0 +1,12 @@
+PROPERTIES
+
+preferredNumberOfChannels=6
+content=44073
+
+LOG
+
+Channels Used: 7
+
+CODEWORDS
+
+111100111111213223142111200
diff --git a/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-7-channels-to-8.png b/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-7-channels-to-8.png
new file mode 100644
index 00000000..e2138acb
Binary files /dev/null and b/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-7-channels-to-8.png differ
diff --git a/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-7-channels-to-8.properties b/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-7-channels-to-8.properties
new file mode 100644
index 00000000..f76dc631
--- /dev/null
+++ b/src/test/resources/uk/org/okapibarcode/backend/channelcode/basic-7-channels-to-8.properties
@@ -0,0 +1,12 @@
+PROPERTIES
+
+preferredNumberOfChannels=7
+content=576689
+
+LOG
+
+Channels Used: 8
+
+CODEWORDS
+
+111100111111213211212213143
diff --git a/src/test/resources/uk/org/okapibarcode/backend/channelcode/invalid-chars.properties b/src/test/resources/uk/org/okapibarcode/backend/channelcode/invalid-chars.properties
new file mode 100644
index 00000000..7d877c17
--- /dev/null
+++ b/src/test/resources/uk/org/okapibarcode/backend/channelcode/invalid-chars.properties
@@ -0,0 +1,7 @@
+PROPERTIES
+
+content=1.2
+
+ERROR
+
+Invalid characters in data
diff --git a/src/test/resources/uk/org/okapibarcode/backend/channelcode/too-few-channels.properties b/src/test/resources/uk/org/okapibarcode/backend/channelcode/too-few-channels.properties
new file mode 100644
index 00000000..8eba40f1
--- /dev/null
+++ b/src/test/resources/uk/org/okapibarcode/backend/channelcode/too-few-channels.properties
@@ -0,0 +1,8 @@
+PROPERTIES
+
+preferredNumberOfChannels=2
+content=7742862
+
+ERROR
+
+Invalid number of channels: 2
diff --git a/src/test/resources/uk/org/okapibarcode/backend/channelcode/too-long.properties b/src/test/resources/uk/org/okapibarcode/backend/channelcode/too-long.properties
new file mode 100644
index 00000000..8e73db78
--- /dev/null
+++ b/src/test/resources/uk/org/okapibarcode/backend/channelcode/too-long.properties
@@ -0,0 +1,7 @@
+PROPERTIES
+
+content=12345678
+
+ERROR
+
+Input data too long
diff --git a/src/test/resources/uk/org/okapibarcode/backend/channelcode/too-many-channels.properties b/src/test/resources/uk/org/okapibarcode/backend/channelcode/too-many-channels.properties
new file mode 100644
index 00000000..6e6fa0df
--- /dev/null
+++ b/src/test/resources/uk/org/okapibarcode/backend/channelcode/too-many-channels.properties
@@ -0,0 +1,8 @@
+PROPERTIES
+
+preferredNumberOfChannels=9
+content=7742862
+
+ERROR
+
+Invalid number of channels: 9