diff --git a/library/src/main/java/uk/co/alt236/bluetoothlelib/util/IBeaconUtils.java b/library/src/main/java/uk/co/alt236/bluetoothlelib/util/IBeaconUtils.java
index cadc2c9..f38b995 100644
--- a/library/src/main/java/uk/co/alt236/bluetoothlelib/util/IBeaconUtils.java
+++ b/library/src/main/java/uk/co/alt236/bluetoothlelib/util/IBeaconUtils.java
@@ -50,6 +50,9 @@ public class IBeaconUtils {
             }
 
             final int intFromByte = ByteUtils.getIntFromByte(uuid[i]);
+            if(intFromByte <= 0xF){
+                sb.append('0');
+            }
             sb.append(Integer.toHexString(intFromByte));
         }
 
diff --git a/library/src/test/java/uk/co/alt236/bluetoothlelib/util/IBeaconUtilsTest.java b/library/src/test/java/uk/co/alt236/bluetoothlelib/util/IBeaconUtilsTest.java
index 8253383..be5ffdc 100644
--- a/library/src/test/java/uk/co/alt236/bluetoothlelib/util/IBeaconUtilsTest.java
+++ b/library/src/test/java/uk/co/alt236/bluetoothlelib/util/IBeaconUtilsTest.java
@@ -34,6 +34,13 @@ public class IBeaconUtilsTest extends TestCase {
     }
 
     public void testCalculateUuidString() throws Exception {
-
+        assertEquals("00", IBeaconUtils.calculateUuidString(new byte[]{0}));
+        assertEquals("0a", IBeaconUtils.calculateUuidString(new byte[]{10}));
+        assertEquals("0f", IBeaconUtils.calculateUuidString(new byte[]{15}));
+        assertEquals("10", IBeaconUtils.calculateUuidString(new byte[]{16}));
+        assertEquals("7f", IBeaconUtils.calculateUuidString(new byte[]{127}));
+        assertEquals(
+                "00000000-0000-0000-0000-00",
+                IBeaconUtils.calculateUuidString(new byte[]{0,0,0,0,0,0,0,0,0,0,0}));
     }
 }
\ No newline at end of file