diff --git a/src/ol/structs/integerset.js b/src/ol/structs/integerset.js
index b30857e567..441f37d156 100644
--- a/src/ol/structs/integerset.js
+++ b/src/ol/structs/integerset.js
@@ -293,3 +293,23 @@ ol.structs.IntegerSet.prototype.removeRange =
   }
   this.compactRanges_();
 };
+
+
+if (goog.DEBUG) {
+
+  /**
+   * @return {string} String.
+   */
+  ol.structs.IntegerSet.prototype.toString = function() {
+    var arr = this.arr_;
+    var n = arr.length;
+    var result = new Array(n / 2);
+    var resultIndex = 0;
+    var i;
+    for (i = 0; i < n; i += 2) {
+      result[resultIndex++] = arr[i] + '-' + arr[i + 1];
+    }
+    return result.join(', ');
+  };
+
+}
diff --git a/test/spec/ol/structs/integerset.test.js b/test/spec/ol/structs/integerset.test.js
index 964c660dff..367d33c009 100644
--- a/test/spec/ol/structs/integerset.test.js
+++ b/test/spec/ol/structs/integerset.test.js
@@ -116,6 +116,14 @@ describe('ol.structs.IntegerSet', function() {
 
     });
 
+    describe('toString', function() {
+
+      it('returns an empty string', function() {
+        expect(is.toString()).to.be.empty();
+      });
+
+    });
+
   });
 
   describe('with a populated instance', function() {
@@ -342,6 +350,13 @@ describe('ol.structs.IntegerSet', function() {
 
     });
 
+    describe('toString', function() {
+
+      it('returns the expected value', function() {
+        expect(is.toString()).to.be('4-6, 8-10, 12-14');
+      });
+    });
+
   });
 
   describe('with fragmentation', function() {
@@ -427,6 +442,14 @@ describe('ol.structs.IntegerSet', function() {
 
     });
 
+    describe('toString', function() {
+
+      it('returns the expected value', function() {
+        expect(is.toString()).to.be('0-1, 2-4, 5-8, 9-12, 13-15, 16-17');
+      });
+
+    });
+
   });
 
   describe('compared to a slow reference implementation', function() {