diff --git a/lib/type/unit/Unit.js b/lib/type/unit/Unit.js
index 31299e39f..c3aab1d48 100644
--- a/lib/type/unit/Unit.js
+++ b/lib/type/unit/Unit.js
@@ -2988,6 +2988,7 @@ function factory (type, config, load, typed, math) {
     var offset = 0;
     var definition;
     var prefixes;
+    var userBaseUnit;
     if(obj && obj.type === 'Unit') {
       defUnit = obj.clone();
     }
@@ -3001,6 +3002,7 @@ function factory (type, config, load, typed, math) {
       prefixes = obj.prefixes; 
       offset = obj.offset;
       aliases = obj.aliases;
+      userBaseUnit = obj.base;
     }
     else {
       throw new TypeError('Cannot create unit "' + name + '" from "' + obj.toString() + '": expecting "string" or "Unit" or "Object"');
@@ -3059,16 +3061,33 @@ function factory (type, config, load, typed, math) {
         value: 1,
         dimensions: BASE_UNITS[baseName].dimensions,
         prefixes: prefixes,
-        offset: offset
+        offset: offset,
+        base: baseName
       };
     }
     else {
       newUnit = {
         name: name,
         value: defUnit.value,
-        dimensions: defUnit.dimensions.splice(0),
+        dimensions: defUnit.dimensions.slice(0),
         prefixes: prefixes,
-        offset: offset
+        offset: offset,
+        base: userBaseUnit
+      };
+
+      // Register the userBaseUnit
+      if(userBaseUnit) {
+        BASE_UNITS[userBaseUnit] = {
+          dimensions: newUnit.dimensions.slice(0),
+          key: userBaseUnit
+        };
+
+        if(!currentUnitSystem.hasOwnProperty(userBaseUnit)) {
+          currentUnitSystem[userBaseUnit] = {
+            unit: newUnit,
+            prefix: PREFIXES.NONE['']
+          };
+        }
       }
     }