diff --git a/briar-android/src/main/java/org/briarproject/briar/android/conversation/AttachmentController.java b/briar-android/src/main/java/org/briarproject/briar/android/conversation/AttachmentController.java
index b8754e755..2d85e2668 100644
--- a/briar-android/src/main/java/org/briarproject/briar/android/conversation/AttachmentController.java
+++ b/briar-android/src/main/java/org/briarproject/briar/android/conversation/AttachmentController.java
@@ -4,6 +4,7 @@ import android.content.res.Resources;
 import android.graphics.BitmapFactory;
 import android.support.annotation.Nullable;
 import android.support.media.ExifInterface;
+import android.webkit.MimeTypeMap;
 
 import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
@@ -132,8 +133,14 @@ class AttachmentController {
 			thumbnailSize =
 					getThumbnailSize(size.width, size.height, size.mimeType);
 		}
+		// get file extension
+		MimeTypeMap mimeTypeMap = MimeTypeMap.getSingleton();
+		String extension = mimeTypeMap.getExtensionFromMimeType(size.mimeType);
+		if (extension == null) {
+			return new AttachmentItem(messageId, 0, 0, "", "", 0, 0, true);
+		}
 		return new AttachmentItem(messageId, size.width, size.height,
-				size.mimeType, thumbnailSize.width, thumbnailSize.height,
+				size.mimeType, extension, thumbnailSize.width, thumbnailSize.height,
 				size.error);
 	}
 
diff --git a/briar-android/src/main/java/org/briarproject/briar/android/conversation/AttachmentItem.java b/briar-android/src/main/java/org/briarproject/briar/android/conversation/AttachmentItem.java
index 9e36e848a..bbc7c1f6b 100644
--- a/briar-android/src/main/java/org/briarproject/briar/android/conversation/AttachmentItem.java
+++ b/briar-android/src/main/java/org/briarproject/briar/android/conversation/AttachmentItem.java
@@ -14,7 +14,7 @@ public class AttachmentItem implements Parcelable {
 
 	private final MessageId messageId;
 	private final int width, height;
-	private final String mimeType;
+	private final String mimeType, extension;
 	private final int thumbnailWidth, thumbnailHeight;
 	private final boolean hasError;
 
@@ -32,11 +32,13 @@ public class AttachmentItem implements Parcelable {
 			};
 
 	AttachmentItem(MessageId messageId, int width, int height, String mimeType,
-			int thumbnailWidth, int thumbnailHeight, boolean hasError) {
+			String extension, int thumbnailWidth, int thumbnailHeight,
+			boolean hasError) {
 		this.messageId = messageId;
 		this.width = width;
 		this.height = height;
 		this.mimeType = mimeType;
+		this.extension = extension;
 		this.thumbnailWidth = thumbnailWidth;
 		this.thumbnailHeight = thumbnailHeight;
 		this.hasError = hasError;
@@ -49,6 +51,7 @@ public class AttachmentItem implements Parcelable {
 		width = in.readInt();
 		height = in.readInt();
 		mimeType = in.readString();
+		extension = in.readString();
 		thumbnailWidth = in.readInt();
 		thumbnailHeight = in.readInt();
 		hasError = in.readByte() != 0;
@@ -70,6 +73,10 @@ public class AttachmentItem implements Parcelable {
 		return mimeType;
 	}
 
+	String getExtension() {
+		return extension;
+	}
+
 	int getThumbnailWidth() {
 		return thumbnailWidth;
 	}
@@ -98,6 +105,7 @@ public class AttachmentItem implements Parcelable {
 		dest.writeInt(width);
 		dest.writeInt(height);
 		dest.writeString(mimeType);
+		dest.writeString(extension);
 		dest.writeInt(thumbnailWidth);
 		dest.writeInt(thumbnailHeight);
 		dest.writeByte((byte) (hasError ? 1 : 0));
diff --git a/briar-android/src/main/java/org/briarproject/briar/android/conversation/ImageViewModel.java b/briar-android/src/main/java/org/briarproject/briar/android/conversation/ImageViewModel.java
index 059f657e3..694887c91 100644
--- a/briar-android/src/main/java/org/briarproject/briar/android/conversation/ImageViewModel.java
+++ b/briar-android/src/main/java/org/briarproject/briar/android/conversation/ImageViewModel.java
@@ -94,10 +94,8 @@ public class ImageViewModel extends AndroidViewModel {
 	 */
 	void saveImage(AttachmentItem attachment) {
 		File file = getImageFile(attachment);
-		saveImage(attachment, () -> getOutputStream(file), () -> {
-			scanFile(getApplication(), new String[] {file.toString()}, null,
-					null);
-		});
+		saveImage(attachment, () -> getOutputStream(file), () -> scanFile(
+				getApplication(), new String[] {file.toString()}, null, null));
 	}
 
 	private void saveImage(AttachmentItem attachment, OutputStreamProvider osp,
@@ -141,7 +139,7 @@ public class ImageViewModel extends AndroidViewModel {
 		//noinspection ResultOfMethodCallIgnored
 		path.mkdirs();
 		String fileName = getFileName();
-		String ext = attachment.getMimeType().replaceFirst("image/", ".");
+		String ext = "." + attachment.getExtension();
 		File file = new File(path, fileName + ext);
 		int i = 1;
 		while (file.exists()) {