diff --git a/NOTES_ON_OPTICAL_PRINTER_TECHNIQUE.md b/NOTES_ON_OPTICAL_PRINTER_TECHNIQUE.md
index f9b5a51..cfc7761 100644
--- a/NOTES_ON_OPTICAL_PRINTER_TECHNIQUE.md
+++ b/NOTES_ON_OPTICAL_PRINTER_TECHNIQUE.md
@@ -439,7 +439,7 @@ A filter which absorbs the ultraviolet, such as Wratten 2B or 2E improves sharpn
 
 Also, printing color film onto color film, or B&W film onto color film, there is color reproduction advantage to using a UV filter.
 
-Some color rawstooks have such filtration built in, some don't.
+Some color rawstocks have such filtration built in, some don't.
 
 Even printing color film onto B&W film there is tonal advantage to using a UV filter.