diff --git a/src/ol/proj/index.js b/src/ol/proj/index.js
index 019398f74e..5ba8582de1 100644
--- a/src/ol/proj/index.js
+++ b/src/ol/proj/index.js
@@ -1,29 +1,14 @@
 goog.provide('ol.proj');
 goog.provide('ol.proj.METERS_PER_UNIT');
 goog.provide('ol.proj.Projection');
-goog.provide('ol.proj.Units');
 
 goog.require('ol');
 goog.require('ol.extent');
 goog.require('ol.obj');
+goog.require('ol.proj.Units');
 goog.require('ol.sphere.NORMAL');
 
 
-/**
- * Projection units: `'degrees'`, `'ft'`, `'m'`, `'pixels'`, `'tile-pixels'` or
- * `'us-ft'`.
- * @enum {string}
- */
-ol.proj.Units = {
-  DEGREES: 'degrees',
-  FEET: 'ft',
-  METERS: 'm',
-  PIXELS: 'pixels',
-  TILE_PIXELS: 'tile-pixels',
-  USFEET: 'us-ft'
-};
-
-
 /**
  * Meters per unit lookup table.
  * @const
diff --git a/src/ol/proj/units.js b/src/ol/proj/units.js
new file mode 100644
index 0000000000..e83994a1c8
--- /dev/null
+++ b/src/ol/proj/units.js
@@ -0,0 +1,16 @@
+goog.provide('ol.proj.Units');
+
+
+/**
+ * Projection units: `'degrees'`, `'ft'`, `'m'`, `'pixels'`, `'tile-pixels'` or
+ * `'us-ft'`.
+ * @enum {string}
+ */
+ol.proj.Units = {
+  DEGREES: 'degrees',
+  FEET: 'ft',
+  METERS: 'm',
+  PIXELS: 'pixels',
+  TILE_PIXELS: 'tile-pixels',
+  USFEET: 'us-ft'
+};