diff --git a/generate-spec b/generate-spec
index 3b5b1d5..5b8f63d 100755
--- a/generate-spec
+++ b/generate-spec
@@ -159,14 +159,20 @@ if (file_exists($definitionsPath)) {
 
 $capabilities = null;
 $publicCapabilities = null;
-$iterator = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($sourceDir));
 $capabilitiesFiles = [];
-foreach ($iterator as $file) {
-	$path = $file->getPathname();
-	if (!str_ends_with($path, ".php")) {
-		continue;
+$capabilitiesDirs = [$sourceDir];
+if ($appIsCore) {
+	$capabilitiesDirs[] = $sourceDir . '/../lib/private';
+}
+foreach ($capabilitiesDirs as $dir) {
+	$iterator = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($dir));
+	foreach ($iterator as $file) {
+		$path = $file->getPathname();
+		if (!str_ends_with($path, ".php")) {
+			continue;
+		}
+		$capabilitiesFiles[] = $path;
 	}
-	$capabilitiesFiles[] = $path;
 }
 sort($capabilitiesFiles);
 foreach ($capabilitiesFiles as $path) {