diff --git a/src/Cache/FileCacheStorage.php b/src/Cache/FileCacheStorage.php
index c5597e51ce..d930f78a41 100644
--- a/src/Cache/FileCacheStorage.php
+++ b/src/Cache/FileCacheStorage.php
@@ -77,11 +77,17 @@ public function save(string $key, string $variableKey, $data): void
 		$this->makeDir($secondDirectory);
 
 		$tmpPath = sprintf('%s/%s.tmp', $this->directory, Random::generate());
+		$errorBefore = error_get_last();
+		$exported = @var_export(new CacheItem($variableKey, $data), true);
+		$errorAfter = error_get_last();
+		if ($errorAfter !== null && $errorBefore !== $errorAfter) {
+			throw new \PHPStan\ShouldNotHappenException(sprintf('Error occurred while saving item %s (%s) to cache: %s', $key, $variableKey, $errorAfter['message']));
+		}
 		FileWriter::write(
 			$tmpPath,
 			sprintf(
 				"<?php declare(strict_types = 1);\n\nreturn %s;",
-				var_export(new CacheItem($variableKey, $data), true)
+				$exported
 			)
 		);