diff --git a/printed/screw_knob.scad b/printed/screw_knob.scad
index bfe35d0..450d628 100644
--- a/printed/screw_knob.scad
+++ b/printed/screw_knob.scad
@@ -34,7 +34,7 @@ knob_waves = 5;
 knob_height = knob_stem_h + knob_thickness;
 function knob_height() = knob_height;
 
-module screw_knob(screw) { //! Generate the STL foe a knob to fit the specified hex screw
+module screw_knob(screw) { //! Generate the STL for a knob to fit the specified hex screw
     stl(str("screw_knob_M", screw_radius(screw) * 20));
 
     knob_stem_r = nut_trap_radius(screw_nut(screw)) + knob_wall;
diff --git a/readme.md b/readme.md
index 21d19b6..8203b0a 100644
--- a/readme.md
+++ b/readme.md
@@ -4102,7 +4102,7 @@ Knob with embedded hex head screw.
 ### Modules
 | Module | Description |
 |:--- |:--- |
-| ```screw_knob(screw)``` | Generate the STL foe a knob to fit the specified hex screw |
+| ```screw_knob(screw)``` | Generate the STL for a knob to fit the specified hex screw |
 | ```screw_knob_assembly(screw, length)``` | Assembly with the screw in place |
 
 ![screw_knob](tests/png/screw_knob.png)