diff --git a/app/src/main/java/sh/sar/isodroid/ui/components/CreateImgDialog.kt b/app/src/main/java/sh/sar/isodroid/ui/components/CreateImgDialog.kt
index 835d741..0864315 100644
--- a/app/src/main/java/sh/sar/isodroid/ui/components/CreateImgDialog.kt
+++ b/app/src/main/java/sh/sar/isodroid/ui/components/CreateImgDialog.kt
@@ -76,9 +76,10 @@ fun CreateImgDialog(
 
     val fullFileName = if (fileName.isNotBlank()) "$fileName.img" else ""
     val fileExists = fullFileName.isNotEmpty() && existingFiles.contains(fullFileName)
+    val hasInvalidChars = fileName.any { !it.isLetterOrDigit() && it !in "-_. ()[]+," }
 
     val isValidInput = fileName.isNotBlank() &&
-            !fileName.contains("/") &&
+            !hasInvalidChars &&
             sizeValue.toLongOrNull()?.let { it > 0 } == true &&
             !fileExists
 
@@ -135,11 +136,11 @@ fun CreateImgDialog(
                     // File name input
                     OutlinedTextField(
                         value = fileName,
-                        onValueChange = { fileName = it.replace("/", "") },
+                        onValueChange = { fileName = it },
                         label = { Text("File Name") },
                         suffix = { Text(".img") },
                         singleLine = true,
-                        isError = fileExists,
+                        isError = fileExists || hasInvalidChars,
                         modifier = Modifier.fillMaxWidth()
                     )
 
@@ -153,6 +154,16 @@ fun CreateImgDialog(
                         )
                     }
 
+                    // Show error if invalid characters
+                    if (hasInvalidChars) {
+                        Spacer(modifier = Modifier.height(8.dp))
+                        Text(
+                            text = "Invalid file name",
+                            style = MaterialTheme.typography.bodySmall,
+                            color = MaterialTheme.colorScheme.error
+                        )
+                    }
+
                     Spacer(modifier = Modifier.height(16.dp))
 
                     // Size input
diff --git a/app/src/main/java/sh/sar/isodroid/ui/components/FileContextMenu.kt b/app/src/main/java/sh/sar/isodroid/ui/components/FileContextMenu.kt
index 065ab9f..88a1152 100644
--- a/app/src/main/java/sh/sar/isodroid/ui/components/FileContextMenu.kt
+++ b/app/src/main/java/sh/sar/isodroid/ui/components/FileContextMenu.kt
@@ -170,7 +170,8 @@ private fun RenameDialog(
     val nameWithoutExtension = currentName.removeSuffix(extension)
 
     var newName by remember { mutableStateOf(nameWithoutExtension) }
-    val isValid = newName.isNotBlank() && !newName.contains("/")
+    val hasInvalidChars = newName.any { !it.isLetterOrDigit() && it !in "-_. ()[]+," }
+    val isValid = newName.isNotBlank() && !hasInvalidChars
 
     AlertDialog(
         onDismissRequest = onDismiss,
@@ -179,12 +180,22 @@ private fun RenameDialog(
             Column {
                 OutlinedTextField(
                     value = newName,
-                    onValueChange = { newName = it.replace("/", "") },
+                    onValueChange = { newName = it },
                     label = { Text("File Name") },
                     suffix = { Text(extension) },
                     singleLine = true,
+                    isError = hasInvalidChars,
                     modifier = Modifier.fillMaxWidth()
                 )
+
+                if (hasInvalidChars) {
+                    Spacer(modifier = Modifier.height(8.dp))
+                    Text(
+                        text = "Invalid file name",
+                        style = MaterialTheme.typography.bodySmall,
+                        color = MaterialTheme.colorScheme.error
+                    )
+                }
             }
         },
         confirmButton = {
diff --git a/app/src/main/java/sh/sar/isodroid/ui/screens/SettingsScreen.kt b/app/src/main/java/sh/sar/isodroid/ui/screens/SettingsScreen.kt
index 8207a00..3557910 100644
--- a/app/src/main/java/sh/sar/isodroid/ui/screens/SettingsScreen.kt
+++ b/app/src/main/java/sh/sar/isodroid/ui/screens/SettingsScreen.kt
@@ -489,6 +489,7 @@ private fun DirectoryBrowserDialog(
         scope.launch {
             val trimmedName = name.trim()
             if (trimmedName.isEmpty()) return@launch
+
             val newPath = "$currentPath/$trimmedName"
             RootManager.executeCommand("mkdir -p \"$newPath\"")
             // Create marker file to indicate this folder was created by the app
@@ -716,6 +717,9 @@ private fun DirectoryBrowserDialog(
 
     // Create folder dialog
     if (showCreateFolderDialog) {
+        val hasInvalidChars = newFolderName.any { !it.isLetterOrDigit() && it !in "-_. ()[]+," }
+        val isValidInput = newFolderName.isNotBlank() && !hasInvalidChars
+
         AlertDialog(
             onDismissRequest = {
                 showCreateFolderDialog = false
@@ -723,24 +727,36 @@ private fun DirectoryBrowserDialog(
             },
             title = { Text("Create Directory") },
             text = {
-                OutlinedTextField(
-                    value = newFolderName,
-                    onValueChange = { newFolderName = it },
-                    label = { Text("Directory name") },
-                    singleLine = true,
-                    modifier = Modifier.fillMaxWidth()
-                )
+                Column {
+                    OutlinedTextField(
+                        value = newFolderName,
+                        onValueChange = { newFolderName = it },
+                        label = { Text("Directory name") },
+                        singleLine = true,
+                        isError = hasInvalidChars,
+                        modifier = Modifier.fillMaxWidth()
+                    )
+
+                    if (hasInvalidChars) {
+                        Spacer(modifier = Modifier.height(8.dp))
+                        Text(
+                            text = "Invalid directory name",
+                            style = MaterialTheme.typography.bodySmall,
+                            color = MaterialTheme.colorScheme.error
+                        )
+                    }
+                }
             },
             confirmButton = {
                 TextButton(
                     onClick = {
-                        if (newFolderName.isNotBlank()) {
+                        if (isValidInput) {
                             createFolder(newFolderName)
                             showCreateFolderDialog = false
                             newFolderName = ""
                         }
                     },
-                    enabled = newFolderName.isNotBlank()
+                    enabled = isValidInput
                 ) {
                     Text("Create")
                 }