diff --git a/src/FileRise/Domain/DiskUsageModel.php b/src/FileRise/Domain/DiskUsageModel.php
index 8144d16..0733a46 100644
--- a/src/FileRise/Domain/DiskUsageModel.php
+++ b/src/FileRise/Domain/DiskUsageModel.php
@@ -632,8 +632,8 @@ public static function getSummary(int $maxTopFolders = 5, int $maxTopFilesPrevie
                 continue;
             }
 
-            $total = @disk_total_space($real);
-            $free  = @disk_free_space($real);
+            $total = function_exists('disk_total_space') ? @disk_total_space($real) : false;
+            $free  = function_exists('disk_free_space') ? @disk_free_space($real) : false;
             if ($total === false || $free === false || $total <= 0) {
                 continue;
             }
diff --git a/src/FileRise/Domain/FileModel.php b/src/FileRise/Domain/FileModel.php
index 3a8aa63..6ef5100 100644
--- a/src/FileRise/Domain/FileModel.php
+++ b/src/FileRise/Domain/FileModel.php
@@ -1616,7 +1616,7 @@ public static function createZipArchive($folder, $files)
                 $totalSize += (int)$sz;
             }
         }
-        $free = @disk_free_space($work);
+        $free = function_exists('disk_free_space') ? @disk_free_space($work) : false;
         // Add ~20MB overhead and a 5% cushion
         if ($free !== false && $totalSize > 0) {
             $needed = (int)ceil($totalSize * 1.05) + (20 * 1024 * 1024);
diff --git a/src/FileRise/Http/Controllers/FolderController.php b/src/FileRise/Http/Controllers/FolderController.php
index 5335d1a..a4cc6f8 100644
--- a/src/FileRise/Http/Controllers/FolderController.php
+++ b/src/FileRise/Http/Controllers/FolderController.php
@@ -2149,7 +2149,7 @@ public function downloadSharedFolder(): void
         }
 
         // Ensure enough free space (best-effort)
-        $free = @disk_free_space($work);
+        $free = function_exists('disk_free_space') ? @disk_free_space($work) : false;
         if ($free !== false && $totalBytes > 0) {
             $needed = (int)ceil($totalBytes * 1.05) + (20 * 1024 * 1024);
             if ($free < $needed) {