diff --git a/Rakefile b/Rakefile
index 727c781..8653b2a 100644
--- a/Rakefile
+++ b/Rakefile
@@ -89,7 +89,7 @@ end
 
 desc "generate printable version (PDF) of schematic"
 rule ".sch.pdf" => ".versioned.sch" do |t|
-  sh "lepton-cli export --color --paper iso_a4 --layout landscape --output #{t.name} #{t.source} 2> /dev/null"
+  sh "lepton-cli export --color --paper=iso_a4 --layout=landscape --output=#{t.name} #{t.source} 2> /dev/null"
 end
 
 desc "generate printable version (PostScript) of board layout"