diff --git a/js/id/actions/modes.js b/js/id/actions/modes.js
index 73913476b..ace2a7e03 100644
--- a/js/id/actions/modes.js
+++ b/js/id/actions/modes.js
@@ -8,18 +8,6 @@ iD.modes._node = function(ll) {
     });
 };
 
-iD.modes.chooseIndex = function(way, point, map) {
-    var dist = iD.util.geo.dist;
-    var projNodes = way.nodes.map(function(n) {
-        return map.projection([n.lon, n.lat]);
-    });
-    for (var i = 0, changes = []; i < projNodes.length - 1; i++) {
-        changes[i] =
-            (dist(projNodes[i], point) + dist(point, projNodes[i + 1])) /
-            dist(projNodes[i], projNodes[i + 1]);
-    }
-    return _.indexOf(changes, _.min(changes)) + 1;
-};
 
 iD.modes.AddPlace = {
     id: 'add-place',
@@ -114,7 +102,7 @@ iD.modes.AddRoad = {
                 node = t.data()[0];
             // snap into an existing way
             } else if (t.data() && t.data()[0] && t.data()[0].type === 'way') {
-                var index = iD.modes.chooseIndex(t.data()[0], d3.mouse(surface.node()), this.map);
+                var index = iD.util.geo.chooseIndex(t.data()[0], d3.mouse(surface.node()), this.map);
                 node = iD.modes._node(this.map.projection.invert(
                     d3.mouse(surface.node())));
                 var connectedWay = this.history.graph().entity(t.data()[0].id);
diff --git a/js/id/util.js b/js/id/util.js
index 4d297d2a7..08cf6a635 100644
--- a/js/id/util.js
+++ b/js/id/util.js
@@ -88,3 +88,16 @@ iD.util.geo.nodeIntersect = function(entity, extent) {
         entity.lat < extent[0][1] &&
         entity.lat > extent[1][1];
 };
+
+iD.util.geo.chooseIndex = function(way, point, map) {
+    var dist = iD.util.geo.dist;
+    var projNodes = way.nodes.map(function(n) {
+        return map.projection([n.lon, n.lat]);
+    });
+    for (var i = 0, changes = []; i < projNodes.length - 1; i++) {
+        changes[i] =
+            (dist(projNodes[i], point) + dist(point, projNodes[i + 1])) /
+            dist(projNodes[i], projNodes[i + 1]);
+    }
+    return _.indexOf(changes, _.min(changes)) + 1;
+};
diff --git a/test/spec/util.js b/test/spec/util.js
index 3ed2127d9..07968e7c7 100644
--- a/test/spec/util.js
+++ b/test/spec/util.js
@@ -22,16 +22,35 @@ describe('Util', function() {
         expect(iD.util.friendlyName({ tags: { name: 'hi', highway: 'Route 5' }})).to.equal('hi');
     });
 
-    describe('#interp', function() {
-        it('interpolates halfway', function() {
-            var a = { lat: 0, lon: 0 },
-            b = { lat: 10, lon: 10 };
-            expect(iD.util.geo.interp(a, b, 0.5)).to.eql({ lat: 5, lon: 5});
+    describe('geo', function() {
+        describe('#interp', function() {
+            it('interpolates halfway', function() {
+                var a = { lat: 0, lon: 0 },
+                b = { lat: 10, lon: 10 };
+                expect(iD.util.geo.interp(a, b, 0.5)).to.eql({ lat: 5, lon: 5});
+            });
+            it('interpolates to one side', function() {
+                var a = { lat: 0, lon: 0 },
+                    b = { lat: 10, lon: 10 };
+                expect(iD.util.geo.interp(a, b, 0)).to.eql({ lat: 0, lon: 0});
+            });
         });
-        it('interpolates to one side', function() {
-            var a = { lat: 0, lon: 0 },
-            b = { lat: 10, lon: 10 };
-            expect(iD.util.geo.interp(a, b, 0)).to.eql({ lat: 0, lon: 0});
+        describe('#dist', function() {
+            it('distance between two same points is zero', function() {
+                var a = [0, 0],
+                    b = [0, 0];
+                expect(iD.util.geo.dist(a, b)).to.eql(0);
+            });
+            it('a straight 10 unit line is 10', function() {
+                var a = [0, 0],
+                    b = [10, 0];
+                expect(iD.util.geo.dist(a, b)).to.eql(10);
+            });
+            it('a pythagorean triangle is right', function() {
+                var a = [0, 0],
+                    b = [4, 3];
+                expect(iD.util.geo.dist(a, b)).to.eql(5);
+            });
         });
     });
 });