diff --git a/src/components/views/messages/MAudioBody.js b/src/components/views/messages/MAudioBody.js
index 1e9962846c..efc6c4a069 100644
--- a/src/components/views/messages/MAudioBody.js
+++ b/src/components/views/messages/MAudioBody.js
@@ -69,6 +69,12 @@ export default class MAudioBody extends React.Component {
         }
     }
 
+    componentWillUnmount() {
+        if (this.state.decryptedUrl) {
+            URL.revokeObjectURL(this.state.decryptedUrl);
+        }
+    }
+
     render() {
         const content = this.props.mxEvent.getContent();
 
diff --git a/src/components/views/messages/MImageBody.js b/src/components/views/messages/MImageBody.js
index bb36e9b1ef..c22832467e 100644
--- a/src/components/views/messages/MImageBody.js
+++ b/src/components/views/messages/MImageBody.js
@@ -71,6 +71,7 @@ export default class extends React.Component {
         this.context.matrixClient.on('sync', this.onClientSync);
     }
 
+    // FIXME: factor this out and aplpy it to MVideoBody and MAudioBody too!
     onClientSync(syncState, prevState) {
         if (this.unmounted) return;
         // Consider the client reconnected if there is no error with syncing.
@@ -206,6 +207,13 @@ export default class extends React.Component {
         dis.unregister(this.dispatcherRef);
         this.context.matrixClient.removeListener('sync', this.onClientSync);
         this._afterComponentWillUnmount();
+
+        if (this.state.decryptedUrl) {
+            URL.revokeObjectURL(this.state.decryptedUrl);
+        }
+        if (this.state.decryptedThumbnailUrl) {
+            URL.revokeObjectURL(this.state.decryptedThumbnailUrl);
+        }
     }
 
     // To be overridden by subclasses (e.g. MStickerBody) for further
diff --git a/src/components/views/messages/MVideoBody.js b/src/components/views/messages/MVideoBody.js
index 345c3f02e2..5365daee03 100644
--- a/src/components/views/messages/MVideoBody.js
+++ b/src/components/views/messages/MVideoBody.js
@@ -120,6 +120,15 @@ module.exports = React.createClass({
         }
     },
 
+    componentWillUnmount: function() {
+        if (this.state.decryptedUrl) {
+            URL.revokeObjectURL(this.state.decryptedUrl);
+        }
+        if (this.state.decryptedThumbnailUrl) {
+            URL.revokeObjectURL(this.state.decryptedThumbnailUrl);
+        }
+    },
+
     render: function() {
         const content = this.props.mxEvent.getContent();