diff --git a/Lib/gftools/builder/operations/autohintOTF.py b/Lib/gftools/builder/operations/autohintOTF.py
index 07cfd094..89f02851 100644
--- a/Lib/gftools/builder/operations/autohintOTF.py
+++ b/Lib/gftools/builder/operations/autohintOTF.py
@@ -3,4 +3,4 @@
 
 class AutohintOTF(OperationBase):
     description = "Run otfautohint"
-    rule = "otfautohint $args -o $out $in \\|\\| otfautohint $args -o $out $in --no-zones-stems"
+    rule = "otfautohint $args -o \"$out\" \"$in\" \\|\\| otfautohint $args -o \"$out\" \"$in\" --no-zones-stems"