diff --git a/src/matrix/storage/sortkey.js b/src/matrix/storage/sortkey.js
index 58cd3e78..25e45ce6 100644
--- a/src/matrix/storage/sortkey.js
+++ b/src/matrix/storage/sortkey.js
@@ -1,29 +1,42 @@
 const MIN_INT32 = -2147483648;
+const MID_INT32 = 0;
 const MAX_INT32 = 2147483647;
 
+const MIN_UINT32 = 0;
+const MID_UINT32 = 2147483647;
+const MAX_UINT32 = 4294967295;
+
+const MIN = MIN_UINT32;
+const MID = MID_UINT32;
+const MAX = MAX_UINT32;
+
 export default class SortKey {
 	constructor(buffer) {
 		if (buffer) {
-			this._keys = new Int32Array(buffer, 2);
+			this._keys = new DataView(buffer);
 		} else {
-			this._keys = new Int32Array(2);
+			this._keys = new DataView(new ArrayBuffer(8));
+			// start default key right at the middle gap key, min event key
+			// so we have the same amount of key address space either way
+			this.gapKey = MID;
+			this.eventKey = MIN;
 		}
 	}
 
 	get gapKey() {
-		return this._keys[0];
+		return this._keys.getUint32(0, false);
 	}
 
 	set gapKey(value) {
-		this._keys[0] = value;
+		return this._keys.setUint32(0, value, false);
 	}
 
 	get eventKey() {
-		return this._keys[1];
+		return this._keys.getUint32(4, false);
 	}
 
 	set eventKey(value) {
-		this._keys[1] = value;
+		return this._keys.setUint32(4, value, false);
 	}
 
 	get buffer() {
@@ -33,7 +46,7 @@ export default class SortKey {
 	nextKeyWithGap() {
 		const k = new SortKey();
 		k.gapKey = this.gapKey + 1;
-		k.eventKey = 0;
+		k.eventKey = MIN;
 		return k;
 	}
 
@@ -60,15 +73,15 @@ export default class SortKey {
 
 	static get maxKey() {
 		const maxKey = new SortKey();
-		maxKey.gapKey = MAX_INT32;
-		maxKey.eventKey = MAX_INT32;
+		maxKey.gapKey = MAX;
+		maxKey.eventKey = MAX;
 		return maxKey;
 	}
 
 	static get minKey() {
 		const minKey = new SortKey();
-		minKey.gapKey = MIN_INT32;
-		minKey.eventKey = MIN_INT32;
+		minKey.gapKey = MIN;
+		minKey.eventKey = MIN;
 		return minKey;
 	}
 
@@ -82,8 +95,8 @@ export function tests() {
 	return {
 		test_default_key(assert) {
 			const k = new SortKey();
-			assert.equal(k.gapKey, 0);
-			assert.equal(k.eventKey, 0);
+			assert.equal(k.gapKey, MID);
+			assert.equal(k.eventKey, MIN);
 		},
 
 		test_inc(assert) {
@@ -100,24 +113,61 @@ export function tests() {
 		test_min_key(assert) {
 			const minKey = SortKey.minKey;
 			const k = new SortKey();
-			assert(minKey.gapKey < k.gapKey);
-			assert(minKey.eventKey < k.eventKey);
+			assert(minKey.gapKey <= k.gapKey);
+			assert(minKey.eventKey <= k.eventKey);
 		},
 
 		test_max_key(assert) {
 			const maxKey = SortKey.maxKey;
 			const k = new SortKey();
-			assert(maxKey.gapKey > k.gapKey);
-			assert(maxKey.eventKey > k.eventKey);
+			assert(maxKey.gapKey >= k.gapKey);
+			assert(maxKey.eventKey >= k.eventKey);
 		},
 
 		test_immutable(assert) {
 			const a = new SortKey();
 			const gapKey = a.gapKey;
-			const eventKey = a.gapKey;
+			const eventKey = a.eventKey;
 			a.nextKeyWithGap();
 			assert.equal(a.gapKey, gapKey);
 			assert.equal(a.eventKey, eventKey);
+		},
+
+		test_cmp_gapkey_first(assert) {
+			const a = new SortKey();
+			const b = new SortKey();
+			a.gapKey = 2;
+			a.eventKey = 1;
+			b.gapKey = 1;
+			b.eventKey = 100000;
+			assert(b < a);
+			assert(a > b);
+		},
+
+		test_cmp_eventkey_second(assert) {
+			const a = new SortKey();
+			const b = new SortKey();
+			a.gapKey = 1;
+			a.eventKey = 100000;
+			b.gapKey = 1;
+			b.eventKey = 2;
+			assert(b.buffer < a.buffer);
+			assert(a.buffer > b.buffer);
+		},
+
+		test_cmp_max_larger_than_min(assert) {
+			assert(SortKey.minKey < SortKey.maxKey);
+		},
+
+		test_cmp_gapkey_first_large(assert) {
+			const a = new SortKey();
+			const b = new SortKey();
+			a.gapKey = MAX;
+			a.eventKey = MIN;
+			b.gapKey = MIN;
+			b.eventKey = MAX;
+			assert(b < a);
+			assert(a > b);
 		}
 	};
 }