diff --git a/app/src/main/java/com/dazuoye/filemanager/document_page.kt b/app/src/main/java/com/dazuoye/filemanager/document_page.kt
index bb96bb3..765f64a 100644
--- a/app/src/main/java/com/dazuoye/filemanager/document_page.kt
+++ b/app/src/main/java/com/dazuoye/filemanager/document_page.kt
@@ -170,7 +170,7 @@ class document_page : AppCompatActivity() {
           }
           val name = uri.path?.split('/')?.last() ?: "somePastedItem"
           val ext = name.split('.').last()
-          if (!"$ext.".matches(regex)) {
+          if (!".$ext".matches(regex)) {
             Toast.makeText(this, getString(R.string.error_nothing_to_paste), Toast.LENGTH_SHORT)
               .show()
             return@showItemAlert
diff --git a/app/src/main/java/com/dazuoye/filemanager/music_page.kt b/app/src/main/java/com/dazuoye/filemanager/music_page.kt
index af0ad7d..e9ff0f4 100644
--- a/app/src/main/java/com/dazuoye/filemanager/music_page.kt
+++ b/app/src/main/java/com/dazuoye/filemanager/music_page.kt
@@ -151,7 +151,7 @@ class music_page : AppCompatActivity() {
           }
           val name = uri.path?.split('/')?.last() ?: "somePastedItem"
           val ext = name.split('.').last()
-          if (!"$ext.".matches(MusicLister.regex)) {
+          if (!".$ext".matches(MusicLister.regex)) {
             Toast.makeText(this, getString(R.string.error_nothing_to_paste), Toast.LENGTH_SHORT)
               .show()
             return@showItemAlert
diff --git a/app/src/main/java/com/dazuoye/filemanager/picture_page.kt b/app/src/main/java/com/dazuoye/filemanager/picture_page.kt
index 380c160..681ee04 100644
--- a/app/src/main/java/com/dazuoye/filemanager/picture_page.kt
+++ b/app/src/main/java/com/dazuoye/filemanager/picture_page.kt
@@ -152,7 +152,7 @@ class picture_page : AppCompatActivity() {
           }
           val name = uri.path?.split('/')?.last() ?: "somePastedItem"
           val ext = name.split('.').last()
-          if (!"$ext.".matches(ImageLister.regex)) {
+          if (!".$ext".matches(ImageLister.regex)) {
             Toast.makeText(this, getString(R.string.error_nothing_to_paste), Toast.LENGTH_SHORT)
               .show()
             return@showItemAlert
diff --git a/app/src/main/java/com/dazuoye/filemanager/video_page.kt b/app/src/main/java/com/dazuoye/filemanager/video_page.kt
index 8f55882..3ba5407 100644
--- a/app/src/main/java/com/dazuoye/filemanager/video_page.kt
+++ b/app/src/main/java/com/dazuoye/filemanager/video_page.kt
@@ -151,7 +151,7 @@ class video_page : AppCompatActivity() {
           }
           val name = uri.path?.split('/')?.last() ?: "somePastedItem"
           val ext = name.split('.').last()
-          if (!"$ext.".matches(VideoLister.regex)) {
+          if (!".$ext".matches(VideoLister.regex)) {
             Toast.makeText(this, getString(R.string.error_nothing_to_paste), Toast.LENGTH_SHORT)
               .show()
             return@showItemAlert