diff --git a/development/mutagen/README b/development/mutagen/README
index 9356e2d898..b22c7ff981 100644
--- a/development/mutagen/README
+++ b/development/mutagen/README
@@ -14,7 +14,4 @@ individual packet/page level.
 Mutagen works with Python 2.7, 3.3+ and has no dependencies outside
 the Python standard library.
 
-NOTE: to build mutagen with python3 run the slackbuild with option
-PYTHON3=yes.
-
- # PYTHON3=yes ./mutagen.SlackBuild
+Optional dependency: python3
diff --git a/development/mutagen/mutagen.SlackBuild b/development/mutagen/mutagen.SlackBuild
index 346ff70570..8e01169988 100644
--- a/development/mutagen/mutagen.SlackBuild
+++ b/development/mutagen/mutagen.SlackBuild
@@ -2,7 +2,7 @@
 #
 # Slackware build script for mutagen.
 #
-# Copyright 2016-2019  Edinaldo P. Silva, Rio de Janeiro, Brazil.
+# Copyright 2016-2020  Edinaldo P. Silva, Rio de Janeiro, Brazil.
 # Copyright 2016  Dugan Chen (thedoogster [at] gmail [dot] [com])
 # Copyright 2008  Frank Caraballo <fecaraballo{at}gmail{dot}com>
 # All rights reserved.
@@ -26,7 +26,7 @@
 
 PRGNAM=mutagen
 VERSION=${VERSION:-1.43.0}
-BUILD=${BUILD:-1}
+BUILD=${BUILD:-2}
 TAG=${TAG:-_SBo}
 
 if [ -z "$ARCH" ]; then
@@ -74,12 +74,10 @@ find -L . \
  \( -perm 666 -o -perm 664 -o -perm 600 -o -perm 444 -o -perm 440 -o -perm 400 \) \
  -exec chmod 644 {} \;
 
-python setup.py build
 python setup.py install --root $PKG
 
-# Build mutagen with python3. Default is no.
-if [ "${PYTHON3:-no}" == "yes" ]; then
-  python3 setup.py build
+# Install python3 bindings.
+if $(python3 -c 'import sys' 2>/dev/null); then
   python3 setup.py install --root=$PKG
 fi