diff --git a/library/puppet b/library/puppet
index edc3516..0823656 100644
--- a/library/puppet
+++ b/library/puppet
@@ -197,6 +197,8 @@ def main():
         cmd = "%s apply --detailed-exitcodes " % base_cmd
         if p['logdest'] == 'syslog':
             cmd += "--logdest syslog "
+        if p['show_diff']:
+            cmd += "--show_diff "
         if p['environment']:
             cmd += "--environment '%s' " % p['environment']
         if module.check_mode: