diff --git a/spec/unit/crypto/algorithms/megolm.spec.js b/spec/unit/crypto/algorithms/megolm.spec.js
index ec7e65d41..18f4e1343 100644
--- a/spec/unit/crypto/algorithms/megolm.spec.js
+++ b/spec/unit/crypto/algorithms/megolm.spec.js
@@ -119,29 +119,32 @@ describe("MegolmDecryption", function() {
                 },
             };
 
-            expect(megolmDecryption.hasKeysForKeyRequest(keyRequest))
-                .toBe(true);
+            return megolmDecryption.hasKeysForKeyRequest(
+                keyRequest,
+            ).then((hasKeys) => {
+                expect(hasKeys).toBe(true);
 
-            // set up some pre-conditions for the share call
-            const deviceInfo = {};
-            mockCrypto.getStoredDevice.andReturn(deviceInfo);
+                // set up some pre-conditions for the share call
+                const deviceInfo = {};
+                mockCrypto.getStoredDevice.andReturn(deviceInfo);
 
-            const awaitEnsureSessions = new Promise((res, rej) => {
-                mockOlmLib.ensureOlmSessionsForDevices.andCall(() => {
-                    res();
-                    return Promise.resolve({'@alice:foo': {'alidevice': {
-                        sessionId: 'alisession',
-                    }}});
+                const awaitEnsureSessions = new Promise((res, rej) => {
+                    mockOlmLib.ensureOlmSessionsForDevices.andCall(() => {
+                        res();
+                        return Promise.resolve({'@alice:foo': {'alidevice': {
+                            sessionId: 'alisession',
+                        }}});
+                    });
                 });
-            });
 
-            mockBaseApis.sendToDevice = expect.createSpy();
+                mockBaseApis.sendToDevice = expect.createSpy();
 
-            // do the share
-            megolmDecryption.shareKeysWithDevice(keyRequest);
+                // do the share
+                megolmDecryption.shareKeysWithDevice(keyRequest);
 
-            // it's asynchronous, so we have to wait a bit
-            return awaitEnsureSessions.then(() => {
+                // it's asynchronous, so we have to wait a bit
+                return awaitEnsureSessions;
+            }).then(() => {
                 // check that it called encryptMessageForDevice with
                 // appropriate args.
                 expect(mockOlmLib.encryptMessageForDevice.calls.length)
diff --git a/src/crypto/algorithms/base.js b/src/crypto/algorithms/base.js
index 661455070..15f8aed25 100644
--- a/src/crypto/algorithms/base.js
+++ b/src/crypto/algorithms/base.js
@@ -20,6 +20,8 @@ limitations under the License.
  * @module
  */
 
+import Promise from 'bluebird';
+
 /**
  * map of registered encryption algorithm classes. A map from string to {@link
  * module:crypto/algorithms/base.EncryptionAlgorithm|EncryptionAlgorithm} class
@@ -143,11 +145,11 @@ class DecryptionAlgorithm {
      * Determine if we have the keys necessary to respond to a room key request
      *
      * @param {module:crypto~IncomingRoomKeyRequest} keyRequest
-     * @return {boolean} true if we have the keys and could (theoretically) share
+     * @return {Promise<boolean>} true if we have the keys and could (theoretically) share
      *  them; else false.
      */
     hasKeysForKeyRequest(keyRequest) {
-        return false;
+        return Promise.resolve(false);
     }
 
     /**
diff --git a/src/crypto/algorithms/megolm.js b/src/crypto/algorithms/megolm.js
index eb5505e03..948f1f89b 100644
--- a/src/crypto/algorithms/megolm.js
+++ b/src/crypto/algorithms/megolm.js
@@ -719,7 +719,7 @@ MegolmDecryption.prototype.onRoomKeyEvent = function(event) {
 /**
  * @inheritdoc
  */
-MegolmDecryption.prototype.hasKeysForKeyRequest = function(keyRequest) {
+MegolmDecryption.prototype.hasKeysForKeyRequest = async function(keyRequest) {
     const body = keyRequest.requestBody;
 
     return this._olmDevice.hasInboundSessionKeys(
diff --git a/src/crypto/index.js b/src/crypto/index.js
index eb3723fe5..6c28bce3f 100644
--- a/src/crypto/index.js
+++ b/src/crypto/index.js
@@ -1131,7 +1131,7 @@ Crypto.prototype._processReceivedRoomKeyRequest = async function(req) {
         return;
     }
 
-    if (!decryptor.hasKeysForKeyRequest(req)) {
+    if (!await decryptor.hasKeysForKeyRequest(req)) {
         console.log(
             `room key request for unknown session ${roomId} / ` +
                 body.session_id,