diff --git a/Makefile b/Makefile
index 06e30a9..8f42579 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 export TARGET = iphone:clang:13.0:10.3
 export ARCHS = arm64 arm64e
-export VERSION = 0.9.10
+export VERSION = 0.9.11
 export DEBUG = no
 CC = xcrun -sdk ${THEOS}/sdks/iPhoneOS13.0.sdk clang -arch arm64 -arch arm64e -miphoneos-version-min=10.3
 LDID = ldid
diff --git a/control b/control
index 3f7bc44..7866a26 100644
--- a/control
+++ b/control
@@ -1,5 +1,5 @@
 Package: com.michael.TimeMachine
-Version: 0.9.10
+Version: 0.9.11
 Section: Tweaks
 Name: TimeMachine on iOS
 Author: halo_michael <yc992147156@me.com>
diff --git a/setTimeMachine/setTimeMachine.m b/setTimeMachine/setTimeMachine.m
index aabc073..395066d 100644
--- a/setTimeMachine/setTimeMachine.m
+++ b/setTimeMachine/setTimeMachine.m
@@ -186,8 +186,8 @@ int main(int argc, char **argv) {
     }
 
     NSString *filePath = [[NSString alloc] initWithUTF8String:filesystem];
-    while ([filePath characterAtIndex:([filePath length] - 1)] == '/' && [filePath length] != 1) {
-        filePath = [filePath substringToIndex:([filePath length] - 1)];
+    while ([filePath characterAtIndex:([[NSNumber numberWithUnsignedInteger:[filePath length]] intValue] - 1)] == '/' && [[NSNumber numberWithUnsignedInteger:[filePath length]] intValue] != 1) {
+        filePath = [filePath substringToIndex:([[NSNumber numberWithUnsignedInteger:[filePath length]] intValue] - 1)];
     }
     NSError *error = nil;
     NSMutableDictionary *fileInfo = [NSMutableDictionary dictionaryWithDictionary:[[NSFileManager defaultManager] attributesOfItemAtPath:filePath error:&error]];