diff --git a/server/texture-sync-server/src/persistency/mod.rs b/server/texture-sync-server/src/persistency/mod.rs
index 33c900b..8de3ec2 100644
--- a/server/texture-sync-server/src/persistency/mod.rs
+++ b/server/texture-sync-server/src/persistency/mod.rs
@@ -199,20 +199,20 @@ impl DataStore {
         self.textures.iter()
     }
 
-    pub fn extract_hash(filename: &std::ffi::OsStr) -> Option<Sha256> {
-        // directly return None for invalidly encoded file names
-        let str_name = filename.to_str()?;
-        let hash = Sha256::from_hex(str_name)?;
-
-        // check back to ignore names with lowercase letters
-        if hash.as_hex_string() == str_name {
-            Some(hash)
-        } else {
-            None
-        }
-    }
-
     pub fn garbage_collect(&mut self) -> io::Result<()> {
+        fn extract_hash(filename: &std::ffi::OsStr) -> Option<Sha256> {
+            // directly return None for invalidly encoded file names
+            let str_name = filename.to_str()?;
+            let hash = Sha256::from_hex(str_name)?;
+
+            // check back to ignore names with lowercase letters
+            if hash.as_hex_string() == str_name {
+                Some(hash)
+            } else {
+                None
+            }
+        }
+
         let texture_dir = std::fs::read_dir(self.texture_base_path())?;
 
         let mut hashs_on_disk = HashSet::new();
@@ -222,7 +222,7 @@ impl DataStore {
                 Some(name) => name,
                 None => continue,
             };
-            match Self::extract_hash(filename) {
+            match extract_hash(filename) {
                 Some(hash) => {
                     hashs_on_disk.insert(hash);
                 }