diff --git a/composer.json b/composer.json
index 9810e45..4d05c7d 100644
--- a/composer.json
+++ b/composer.json
@@ -1,7 +1,7 @@
 {
     "name": "trexima/harvey-client",
     "description": "Client for Harvey API v2",
-    "version": "1.3.1",
+    "version": "1.3.2",
     "type": "library",
     "license": "MIT",
     "authors": [
diff --git a/src/Client.php b/src/Client.php
index 1763411..94990c9 100644
--- a/src/Client.php
+++ b/src/Client.php
@@ -179,12 +179,17 @@ public function searchIsco(?string $title = null, ?int $workArea = null, ?string
         if ($perPage === 0) {
             $args['pagination'] = false;
         }
-        $cacheKey = 'search-isco-' . crc32(json_encode($args));
-        $result = $this->cache->get($cacheKey, function (ItemInterface $item) use ($args) {
-            $item->expiresAfter($this->cacheTtl);
+        if ($json = json_encode($args)) {
+            $cacheKey = 'search-isco-' . crc32($json);
+            $result = $this->cache->get($cacheKey, function (ItemInterface $item) use ($args) {
+                $item->expiresAfter($this->cacheTtl);
+                $resource = $this->get('api/isco', $args);
+                return (string)$resource->getBody();
+            });
+        } else {
             $resource = $this->get('api/isco', $args);
-            return (string)$resource->getBody();
-        });
+            $result = (string)$resource->getBody();
+        }
         return $this->jsonDecode($result);
     }