diff --git a/lib/private/Files/Cache/Scanner.php b/lib/private/Files/Cache/Scanner.php
index feefe29d27..03aca1924b 100644
--- a/lib/private/Files/Cache/Scanner.php
+++ b/lib/private/Files/Cache/Scanner.php
@@ -480,7 +480,7 @@ class Scanner extends BasicEmitter implements IScanner {
 		try {
 			$callback();
 			\OC_Hook::emit('Scanner', 'correctFolderSize', array('path' => $path));
-			if ($this->cacheActive) {
+			if ($this->cacheActive && $this->cache instanceof Cache) {
 				$this->cache->correctFolderSize($path);
 			}
 		} catch (\OCP\Files\StorageInvalidException $e) {
diff --git a/lib/private/Files/Cache/Updater.php b/lib/private/Files/Cache/Updater.php
index 3f80f2b616..9e4214ad72 100644
--- a/lib/private/Files/Cache/Updater.php
+++ b/lib/private/Files/Cache/Updater.php
@@ -126,7 +126,9 @@ class Updater implements IUpdater {
 		} else {
 			// scanner didn't provide size info, fallback to full size calculation
 			$sizeDifference = 0;
-			$this->cache->correctFolderSize($path, $data);
+			if ($this->cache instanceof Cache) {
+				$this->cache->correctFolderSize($path, $data);
+			}
 		}
 		$this->correctParentStorageMtime($path);
 		$this->propagator->propagateChange($path, $time, $sizeDifference);
@@ -148,7 +150,9 @@ class Updater implements IUpdater {
 		}
 
 		$this->cache->remove($path);
-		$this->cache->correctFolderSize($parent);
+		if ($this->cache instanceof Cache) {
+			$this->cache->correctFolderSize($parent);
+		}
 		$this->correctParentStorageMtime($path);
 		$this->propagator->propagateChange($path, time());
 	}
@@ -190,8 +194,12 @@ class Updater implements IUpdater {
 			$this->cache->update($fileId, ['mimetype' => $mimeType]);
 		}
 
-		$sourceCache->correctFolderSize($source);
-		$this->cache->correctFolderSize($target);
+		if ($sourceCache instanceof Cache) {
+			$sourceCache->correctFolderSize($source);
+		}
+		if ($this->cache instanceof Cache) {
+			$this->cache->correctFolderSize($target);
+		}
 		if ($sourceUpdater instanceof Updater) {
 			$sourceUpdater->correctParentStorageMtime($source);
 		}
diff --git a/lib/private/Files/Cache/Watcher.php b/lib/private/Files/Cache/Watcher.php
index a00e875a2d..0cf6caf0c2 100644
--- a/lib/private/Files/Cache/Watcher.php
+++ b/lib/private/Files/Cache/Watcher.php
@@ -106,7 +106,9 @@ class Watcher implements IWatcher {
 		if ($cachedData['mimetype'] === 'httpd/unix-directory') {
 			$this->cleanFolder($path);
 		}
-		$this->cache->correctFolderSize($path);
+		if ($this->cache instanceof Cache) {
+			$this->cache->correctFolderSize($path);
+		}
 	}
 
 	/**
diff --git a/lib/private/Files/Cache/Wrapper/CacheJail.php b/lib/private/Files/Cache/Wrapper/CacheJail.php
index 88b0f23a1f..3148d1412f 100644
--- a/lib/private/Files/Cache/Wrapper/CacheJail.php
+++ b/lib/private/Files/Cache/Wrapper/CacheJail.php
@@ -23,6 +23,7 @@
  */
 
 namespace OC\Files\Cache\Wrapper;
+use OC\Files\Cache\Cache;
 
 /**
  * Jail to a subdirectory of the wrapped cache
@@ -233,7 +234,9 @@ class CacheJail extends CacheWrapper {
 	 * @param array $data (optional) meta data of the folder
 	 */
 	public function correctFolderSize($path, $data = null) {
-		$this->cache->correctFolderSize($this->getSourcePath($path), $data);
+		if ($this->cache instanceof Cache) {
+			$this->cache->correctFolderSize($this->getSourcePath($path), $data);
+		}
 	}
 
 	/**
@@ -244,7 +247,12 @@ class CacheJail extends CacheWrapper {
 	 * @return int
 	 */
 	public function calculateFolderSize($path, $entry = null) {
-		return $this->cache->calculateFolderSize($this->getSourcePath($path), $entry);
+		if ($this->cache instanceof Cache) {
+			return $this->cache->calculateFolderSize($this->getSourcePath($path), $entry);
+		} else {
+			return 0;
+		}
+
 	}
 
 	/**
diff --git a/lib/private/Files/Cache/Wrapper/CacheWrapper.php b/lib/private/Files/Cache/Wrapper/CacheWrapper.php
index 8c77e3c340..a6e6e61b8c 100644
--- a/lib/private/Files/Cache/Wrapper/CacheWrapper.php
+++ b/lib/private/Files/Cache/Wrapper/CacheWrapper.php
@@ -240,7 +240,9 @@ class CacheWrapper extends Cache {
 	 * @param array $data (optional) meta data of the folder
 	 */
 	public function correctFolderSize($path, $data = null) {
-		$this->cache->correctFolderSize($path, $data);
+		if ($this->cache instanceof Cache) {
+			$this->cache->correctFolderSize($path, $data);
+		}
 	}
 
 	/**
@@ -251,7 +253,11 @@ class CacheWrapper extends Cache {
 	 * @return int
 	 */
 	public function calculateFolderSize($path, $entry = null) {
-		return $this->cache->calculateFolderSize($path, $entry);
+		if ($this->cache instanceof Cache) {
+			return $this->cache->calculateFolderSize($path, $entry);
+		} else {
+			return 0;
+		}
 	}
 
 	/**