diff --git a/metadata/com.foobnix.pro.pdf.reader.yml b/metadata/com.foobnix.pro.pdf.reader.yml
index db979636d3..22f3f48a9a 100644
--- a/metadata/com.foobnix.pro.pdf.reader.yml
+++ b/metadata/com.foobnix.pro.pdf.reader.yml
@@ -408,7 +408,7 @@ Builds:
     build:
       - pushd ../Builder/
       - ./link_to_mupdf_1.16.1.sh
-    ndk: r21
+    ndk: r21b
 
 MaintainerNotes: Upstream builds separate APKs for each architecture but we build
     an universal APK.