diff --git a/build/libifm.php b/build/libifm.php
index 061fa74..234352c 100644
--- a/build/libifm.php
+++ b/build/libifm.php
@@ -2957,7 +2957,8 @@ function IFM( params ) {
 				array( $this, 'convertToUTF8' )
 			);
 		else
-			$item = utf8_encode( $item );
+			if( function_exists( "mb_check_encoding" ) && ! mb_check_encoding( $item, "UTF-8" ) )
+				$item = utf8_encode( $item );
 	}
 
 	public function checkAuth() {
diff --git a/ifm.php b/ifm.php
index 812b58f..35cd228 100644
--- a/ifm.php
+++ b/ifm.php
@@ -2957,7 +2957,8 @@ function IFM( params ) {
 				array( $this, 'convertToUTF8' )
 			);
 		else
-			$item = utf8_encode( $item );
+			if( function_exists( "mb_check_encoding" ) && ! mb_check_encoding( $item, "UTF-8" ) )
+				$item = utf8_encode( $item );
 	}
 
 	public function checkAuth() {
diff --git a/src/main.php b/src/main.php
index 73ecc0b..620fc05 100644
--- a/src/main.php
+++ b/src/main.php
@@ -886,7 +886,8 @@ f00bar;
 				array( $this, 'convertToUTF8' )
 			);
 		else
-			$item = utf8_encode( $item );
+			if( function_exists( "mb_check_encoding" ) && ! mb_check_encoding( $item, "UTF-8" ) )
+				$item = utf8_encode( $item );
 	}
 
 	public function checkAuth() {