diff --git a/CONTRIBUTING.rst b/CONTRIBUTING.rst
index 3100fb1d1..436136430 100644
--- a/CONTRIBUTING.rst
+++ b/CONTRIBUTING.rst
@@ -113,3 +113,8 @@ include the line in your commit or pull request comment::
 can't be accepted. Git makes this trivial - just use the -s flag when you do
 ``git commit``, having first set ``user.name`` and ``user.email`` git configs
 (which you should have done anyway :)
+
+If you forgot to sign off your commits before making your pull request and are on git 2.17+ 
+you can mass signoff using rebase::
+
+    git rebase --signoff origin/develop
diff --git a/spec/unit/room-member.spec.js b/spec/unit/room-member.spec.js
index 298771128..77c2f7058 100644
--- a/spec/unit/room-member.spec.js
+++ b/spec/unit/room-member.spec.js
@@ -285,5 +285,52 @@ describe("RoomMember", function() {
             member.setMembershipEvent(joinEvent); // no-op
             expect(emitCount).toEqual(1);
         });
+
+        it("should set 'name' to user_id if it is just whitespace", function() {
+            const joinEvent = utils.mkMembership({
+                event: true,
+                mship: "join",
+                user: userA,
+                room: roomId,
+                name: " \u200b ",
+            });
+
+            expect(member.name).toEqual(userA); // default = user_id
+            member.setMembershipEvent(joinEvent);
+            expect(member.name).toEqual(userA); // it should fallback because all whitespace
+        });
+
+        it("should disambiguate users on a fuzzy displayname match", function() {
+            const joinEvent = utils.mkMembership({
+                event: true,
+                mship: "join",
+                user: userA,
+                room: roomId,
+                name: "Alíce\u200b", // note diacritic and zero width char
+            });
+
+            const roomState = {
+                getStateEvents: function(type) {
+                    if (type !== "m.room.member") {
+                        return [];
+                    }
+                    return [
+                        utils.mkMembership({
+                            event: true, mship: "join", room: roomId,
+                            user: userC, name: "Alice",
+                        }),
+                        joinEvent,
+                    ];
+                },
+                getUserIdsWithDisplayName: function(displayName) {
+                    return [userA, userC];
+                },
+            };
+            expect(member.name).toEqual(userA); // default = user_id
+            member.setMembershipEvent(joinEvent, roomState);
+            expect(member.name).toNotEqual("Alíce"); // it should disambig.
+            // user_id should be there somewhere
+            expect(member.name.indexOf(userA)).toNotEqual(-1);
+        });
     });
 });
diff --git a/src/models/room-member.js b/src/models/room-member.js
index e7a4bf88c..ebc8df378 100644
--- a/src/models/room-member.js
+++ b/src/models/room-member.js
@@ -302,22 +302,14 @@ function calculateDisplayName(selfUserId, displayName, roomState) {
         return displayName;
     }
 
-    // First check if the displayname is something we consider truthy
-    // after stripping it of zero width characters and padding spaces
-    const strippedDisplayName = utils.removeHiddenChars(displayName);
-    if (!strippedDisplayName) {
-        return selfUserId;
-    }
-
     // Next check if the name contains something that look like a mxid
     // If it does, it may be someone trying to impersonate someone else
     // Show full mxid in this case
-    // Also show mxid if there are other people with the same displayname
-    // ignoring any zero width chars (unicode 200B-200D)
-    // if their displayname is made up of just zero width chars, show full mxid
+    // Also show mxid if there are other people with the same or similar
+    // displayname, after hidden character removal.
     let disambiguate = /@.+:.+/.test(displayName);
     if (!disambiguate) {
-        const userIds = roomState.getUserIdsWithDisplayName(strippedDisplayName);
+        const userIds = roomState.getUserIdsWithDisplayName(displayName);
         disambiguate = userIds.some((u) => u !== selfUserId);
     }
 
diff --git a/src/models/room-state.js b/src/models/room-state.js
index 3dbd7ff88..95da5396b 100644
--- a/src/models/room-state.js
+++ b/src/models/room-state.js
@@ -75,6 +75,8 @@ function RoomState(roomId, oobMemberFlags = undefined) {
         // userId: RoomMember
     };
     this._updateModifiedTime();
+
+    // stores fuzzy matches to a list of userIDs (applies utils.removeHiddenChars to keys)
     this._displayNameToUserIds = {};
     this._userIdsToDisplayNames = {};
     this._tokenToInvite = {}; // 3pid invite state_key to m.room.member invite
@@ -529,12 +531,12 @@ RoomState.prototype.getLastModifiedTime = function() {
 };
 
 /**
- * Get user IDs with the specified display name.
+ * Get user IDs with the specified or similar display names.
  * @param {string} displayName The display name to get user IDs from.
  * @return {string[]} An array of user IDs or an empty array.
  */
 RoomState.prototype.getUserIdsWithDisplayName = function(displayName) {
-    return this._displayNameToUserIds[displayName] || [];
+    return this._displayNameToUserIds[utils.removeHiddenChars(displayName)] || [];
 };
 
 /**