diff --git a/app/src/main/kotlin/com/simplemobiletools/gallery/activities/ViewPagerActivity.kt b/app/src/main/kotlin/com/simplemobiletools/gallery/activities/ViewPagerActivity.kt
index e29352681..fda440ae3 100644
--- a/app/src/main/kotlin/com/simplemobiletools/gallery/activities/ViewPagerActivity.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/gallery/activities/ViewPagerActivity.kt
@@ -121,8 +121,8 @@ class ViewPagerActivity : SimpleActivity(), ViewPager.OnPageChangeListener, View
 
     override fun onCreateOptionsMenu(menu: Menu): Boolean {
         menuInflater.inflate(R.menu.viewpager_menu, menu)
-        menu.findItem(R.id.menu_set_as_wallpaper).isVisible = getCurrentMedium().isImage
-        menu.findItem(R.id.menu_edit).isVisible = getCurrentMedium().isImage
+        menu.findItem(R.id.menu_set_as_wallpaper).isVisible = getCurrentMedium().isImage()
+        menu.findItem(R.id.menu_edit).isVisible = getCurrentMedium().isImage()
         return true
     }
 
diff --git a/app/src/main/kotlin/com/simplemobiletools/gallery/adapters/MediaAdapter.kt b/app/src/main/kotlin/com/simplemobiletools/gallery/adapters/MediaAdapter.kt
index 75d705f3e..af2719e79 100644
--- a/app/src/main/kotlin/com/simplemobiletools/gallery/adapters/MediaAdapter.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/gallery/adapters/MediaAdapter.kt
@@ -181,7 +181,7 @@ class MediaAdapter(val activity: SimpleActivity, val media: MutableList<Medium>,
 
             val path = medium.path
             val timestampSignature = StringSignature(medium.timestamp.toString())
-            if (medium.isGif) {
+            if (medium.isGif()) {
                 Glide.with(activity).load(path).asGif().diskCacheStrategy(DiskCacheStrategy.NONE).signature(timestampSignature).into(itemView.medium_thumbnail)
             } else {
                 Glide.with(activity).load(path).diskCacheStrategy(DiskCacheStrategy.RESULT).signature(timestampSignature)
diff --git a/app/src/main/kotlin/com/simplemobiletools/gallery/fragments/PhotoFragment.kt b/app/src/main/kotlin/com/simplemobiletools/gallery/fragments/PhotoFragment.kt
index c8154e76a..36ba57bec 100644
--- a/app/src/main/kotlin/com/simplemobiletools/gallery/fragments/PhotoFragment.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/gallery/fragments/PhotoFragment.kt
@@ -27,7 +27,7 @@ class PhotoFragment : ViewPagerFragment(), View.OnClickListener {
             medium.path = context.getRealPathFromURI(Uri.parse(medium.path)) ?: ""
 
         subsamplingView = view.photo_view
-        if (medium.isGif) {
+        if (medium.isGif()) {
             subsamplingView.visibility = View.GONE
             view.gif_view.apply {
                 visibility = View.VISIBLE
diff --git a/app/src/main/kotlin/com/simplemobiletools/gallery/models/Directory.kt b/app/src/main/kotlin/com/simplemobiletools/gallery/models/Directory.kt
index e72d7cad2..c9900d325 100644
--- a/app/src/main/kotlin/com/simplemobiletools/gallery/models/Directory.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/gallery/models/Directory.kt
@@ -5,6 +5,10 @@ import com.simplemobiletools.gallery.SORT_BY_NAME
 import com.simplemobiletools.gallery.SORT_DESCENDING
 
 class Directory(val path: String, val thumbnail: String, val name: String, var mediaCnt: Int, val timestamp: Long, var size: Long) : Comparable<Directory> {
+    companion object {
+        var sorting: Int = 0
+    }
+
     fun addSize(bytes: Long) {
         size += bytes
     }
@@ -14,9 +18,19 @@ class Directory(val path: String, val thumbnail: String, val name: String, var m
         if (sorting and SORT_BY_NAME != 0) {
             res = name.toLowerCase().compareTo(other.name.toLowerCase())
         } else if (sorting and SORT_BY_DATE != 0) {
-            res = if (timestamp > other.timestamp) 1 else -1
+            res = if (timestamp == other.timestamp)
+                0
+            else if (timestamp > other.timestamp)
+                1
+            else
+                -1
         } else {
-            res = if (size > other.size) 1 else -1
+            res = if (size == other.size)
+                0
+            else if (size > other.size)
+                1
+            else
+                -1
         }
 
         if (sorting and SORT_DESCENDING != 0) {
@@ -26,8 +40,4 @@ class Directory(val path: String, val thumbnail: String, val name: String, var m
     }
 
     override fun toString() = "Directory {path=$path, thumbnail=$thumbnail, name=$name, mediaCnt=$mediaCnt, timestamp=$timestamp, size $size}"
-
-    companion object {
-        var sorting: Int = 0
-    }
 }
diff --git a/app/src/main/kotlin/com/simplemobiletools/gallery/models/Medium.kt b/app/src/main/kotlin/com/simplemobiletools/gallery/models/Medium.kt
index 8c2ddd839..81104298b 100644
--- a/app/src/main/kotlin/com/simplemobiletools/gallery/models/Medium.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/gallery/models/Medium.kt
@@ -6,11 +6,14 @@ import com.simplemobiletools.gallery.SORT_DESCENDING
 import java.io.Serializable
 
 class Medium(val name: String, var path: String, val isVideo: Boolean, val timestamp: Long, val size: Long) : Serializable, Comparable<Medium> {
-    val isGif: Boolean
-        get() = path.toLowerCase().endsWith(".gif")
+    companion object {
+        private val serialVersionUID = -6553149466975455L
+        var sorting: Int = 0
+    }
 
-    val isImage: Boolean
-        get() = !isGif && !isVideo
+    fun isGif() = path.toLowerCase().endsWith(".gif")
+
+    fun isImage() = !isGif() && !isVideo
 
     fun getMimeType() = if (isVideo) "video/*" else "image/*"
 
@@ -41,9 +44,4 @@ class Medium(val name: String, var path: String, val isVideo: Boolean, val times
     }
 
     override fun toString() = "Medium {name=$name, path=$path, isVideo=$isVideo, timestamp=$timestamp, size=$size}"
-
-    companion object {
-        private val serialVersionUID = -6553149466975455L
-        var sorting: Int = 0
-    }
 }