diff --git a/vmaf.spec b/vmaf.spec
index 8a2b660..916bad4 100644
--- a/vmaf.spec
+++ b/vmaf.spec
@@ -35,6 +35,7 @@ BuildRequires:  gcc-c++
 BuildRequires:  meson >= 0.47
 BuildRequires:  nasm
 BuildRequires:  pkg-config
+# Need /usr/bin/xxd for build
 BuildRequires:  vim
 Provides:       bundled(libsvm) = 3.18