diff --git a/inc/functions.php b/inc/functions.php
index 895a3adb..b80e2c63 100644
--- a/inc/functions.php
+++ b/inc/functions.php
@@ -1690,12 +1690,19 @@ function buildIndex($global_api = "yes") {
 			if (!$content)
 				break;
 
+			// Tries to avoid rebuilding if the body is the same as the one in cache.
 			if ($config['cache']['enabled']) {
 				$contentHash = md5(json_encode($content['body']));
-				$cacheHit = cache::get('index_cache'. $contentHash);
-				if ($cacheHit)
+				$contentHashKey = '_index_hashed_'. $board . '_' . $page;
+				$cachedHash = cache::get($contentHashKey);
+				if ($cachedHash == $contentHash){
+					if ($config['api']['enabled']) {
+						// this is needed for the thread.json and catalog.json rebuilding below, which includes all pages.
+						$catalog[$page-1] = $content['threads'];
+					}
 					continue;
-				cache::set('index_cache'. $contentHash, "processed", 3600);
+				}
+				cache::set($contentHashKey, $contentHash, 3600);
 			}
 
 			// json api