diff --git a/app/src/main/java/eu/kanade/tachiyomi/data/download/DownloadManager.java b/app/src/main/java/eu/kanade/tachiyomi/data/download/DownloadManager.java
index e4f71632bf..5523351e70 100644
--- a/app/src/main/java/eu/kanade/tachiyomi/data/download/DownloadManager.java
+++ b/app/src/main/java/eu/kanade/tachiyomi/data/download/DownloadManager.java
@@ -28,6 +28,7 @@ import eu.kanade.tachiyomi.data.source.base.Source;
 import eu.kanade.tachiyomi.data.source.model.Page;
 import eu.kanade.tachiyomi.event.DownloadChaptersEvent;
 import eu.kanade.tachiyomi.util.DiskUtils;
+import eu.kanade.tachiyomi.util.UrlUtil;
 import rx.Observable;
 import rx.Subscription;
 import rx.android.schedulers.AndroidSchedulers;
@@ -279,6 +280,15 @@ public class DownloadManager {
     // Get the filename for an image given the page
     private String getImageFilename(Page page) {
         String url = page.getImageUrl();
+        int number = page.getPageNumber() + 1;
+        // Try to preserve file extension
+        if (UrlUtil.isJpg(url)) {
+            return number + ".jpg";
+        } else if (UrlUtil.isPng(url)) {
+            return number + ".png";
+        } else if (UrlUtil.isGif(url)) {
+            return number + ".gif";
+        }
         return Uri.parse(url).getLastPathSegment().replaceAll("[^\\sa-zA-Z0-9.-]", "_");
     }
 
diff --git a/app/src/main/java/eu/kanade/tachiyomi/ui/download/DownloadPresenter.java b/app/src/main/java/eu/kanade/tachiyomi/ui/download/DownloadPresenter.java
index 429180f758..fe69bc884d 100644
--- a/app/src/main/java/eu/kanade/tachiyomi/ui/download/DownloadPresenter.java
+++ b/app/src/main/java/eu/kanade/tachiyomi/ui/download/DownloadPresenter.java
@@ -90,6 +90,7 @@ public class DownloadPresenter extends BasePresenter<DownloadFragment> {
                 .flatMap(tick -> Observable.from(download.pages)
                         .map(Page::getProgress)
                         .reduce((x, y) -> x + y))
+                .onBackpressureLatest()
                 .observeOn(AndroidSchedulers.mainThread())
                 .subscribe(progress -> {
                     if (download.totalProgress != progress) {
diff --git a/app/src/main/java/eu/kanade/tachiyomi/ui/manga/MangaPresenter.java b/app/src/main/java/eu/kanade/tachiyomi/ui/manga/MangaPresenter.java
index 797ea674cf..a24f093e71 100644
--- a/app/src/main/java/eu/kanade/tachiyomi/ui/manga/MangaPresenter.java
+++ b/app/src/main/java/eu/kanade/tachiyomi/ui/manga/MangaPresenter.java
@@ -19,13 +19,13 @@ public class MangaPresenter extends BasePresenter<MangaActivity> {
 
     @State Manga manga;
 
-    private static final int DB_MANGA = 1;
+    private static final int GET_MANGA = 1;
 
     @Override
     protected void onCreate(Bundle savedState) {
         super.onCreate(savedState);
 
-        restartableLatestCache(DB_MANGA, this::getDbMangaObservable, MangaActivity::setManga);
+        restartableLatestCache(GET_MANGA, this::getMangaObservable, MangaActivity::setManga);
 
         if (savedState == null)
             registerForStickyEvents();
@@ -38,7 +38,7 @@ public class MangaPresenter extends BasePresenter<MangaActivity> {
         EventBus.getDefault().removeStickyEvent(MangaEvent.class);
     }
 
-    private Observable<Manga> getDbMangaObservable() {
+    private Observable<Manga> getMangaObservable() {
         return Observable.just(manga)
                 .doOnNext(manga -> EventBus.getDefault().postSticky(new MangaEvent(manga)));
     }
@@ -48,7 +48,7 @@ public class MangaPresenter extends BasePresenter<MangaActivity> {
         EventBus.getDefault().removeStickyEvent(manga);
         unregisterForEvents();
         this.manga = manga;
-        start(DB_MANGA);
+        start(GET_MANGA);
     }
 
 }
diff --git a/app/src/main/java/eu/kanade/tachiyomi/ui/manga/chapter/ChaptersFragment.java b/app/src/main/java/eu/kanade/tachiyomi/ui/manga/chapter/ChaptersFragment.java
index 0ecd4e9395..05c115919d 100644
--- a/app/src/main/java/eu/kanade/tachiyomi/ui/manga/chapter/ChaptersFragment.java
+++ b/app/src/main/java/eu/kanade/tachiyomi/ui/manga/chapter/ChaptersFragment.java
@@ -103,18 +103,6 @@ public class ChaptersFragment extends BaseRxFragment<ChaptersPresenter> implemen
         return view;
     }
 
-    @Override
-    public void onResume() {
-        super.onResume();
-        observeChapterDownloadProgress();
-    }
-
-    @Override
-    public void onPause() {
-        unsubscribeChapterDownloadProgress();
-        super.onPause();
-    }
-
     public void onNextChapters(List<Chapter> chapters) {
         // If the list is empty, fetch chapters from source if the conditions are met
         // We use presenter chapters instead because they are always unfiltered
diff --git a/app/src/main/java/eu/kanade/tachiyomi/util/UrlUtil.java b/app/src/main/java/eu/kanade/tachiyomi/util/UrlUtil.java
index 65e0ea618d..baf7ce9dce 100644
--- a/app/src/main/java/eu/kanade/tachiyomi/util/UrlUtil.java
+++ b/app/src/main/java/eu/kanade/tachiyomi/util/UrlUtil.java
@@ -5,6 +5,10 @@ import java.net.URISyntaxException;
 
 public class UrlUtil {
 
+    private static final String JPG = ".jpg";
+    private static final String PNG = ".png";
+    private static final String GIF = ".gif";
+
     public static String getPath(String s) {
         try {
             URI uri = new URI(s);
@@ -18,4 +22,37 @@ public class UrlUtil {
             return s;
         }
     }
+
+    public static boolean isJpg(String url) {
+        return containsIgnoreCase(url, JPG);
+    }
+
+    public static boolean isPng(String url) {
+        return containsIgnoreCase(url, PNG);
+    }
+
+    public static boolean isGif(String url) {
+        return containsIgnoreCase(url, GIF);
+    }
+
+    public static boolean containsIgnoreCase(String src, String what) {
+        final int length = what.length();
+        if (length == 0)
+            return true; // Empty string is contained
+
+        final char firstLo = Character.toLowerCase(what.charAt(0));
+        final char firstUp = Character.toUpperCase(what.charAt(0));
+
+        for (int i = src.length() - length; i >= 0; i--) {
+            // Quick check before calling the more expensive regionMatches() method:
+            final char ch = src.charAt(i);
+            if (ch != firstLo && ch != firstUp)
+                continue;
+
+            if (src.regionMatches(true, i, what, 0, length))
+                return true;
+        }
+
+        return false;
+    }
 }