diff --git a/modules/behavior/hash.js b/modules/behavior/hash.js
index 728bd8f6b..c311e6b62 100644
--- a/modules/behavior/hash.js
+++ b/modules/behavior/hash.js
@@ -1,5 +1,6 @@
 import * as d3 from 'd3';
 import _ from 'lodash';
+import { geoSphericalDistance } from '../geo';
 import { modeBrowse } from '../modes';
 import { utilQsString, utilStringQs } from '../util';
 
@@ -12,13 +13,21 @@ export function behaviorHash(context) {
     var parser = function(map, s) {
         var q = utilStringQs(s);
         var args = (q.map || '').split('/').map(Number);
+
         if (args.length < 3 || args.some(isNaN)) {
             return true; // replace bogus hash
-        } else if (s !== formatter(map).slice(1)) {
-            var mode = context.mode();
-            if (mode && mode.id.match(/^draw/) !== null) {
+
+        } else if (s !== formatter(map).slice(1)) {   // hash has changed
+            var mode = context.mode(),
+                dist = geoSphericalDistance(map.center(), [args[2], args[1]]),
+                maxdist = 500;
+
+            // Don't allow the hash location to change too much while drawing
+            // This can happen if the user accidently hit the back button.  #3996
+            if (mode && mode.id.match(/^draw/) !== null && dist > maxdist) {
                 context.enter(modeBrowse(context));
             }
+
             map.centerZoom([args[2], Math.min(lat, Math.max(-lat, args[1]))], args[0]);
         }
     };