diff --git a/README.Rmd b/README.Rmd
index 6a82c29..7f7ee26 100644
--- a/README.Rmd
+++ b/README.Rmd
@@ -85,7 +85,7 @@ fix_dates(example.df, "example", month.impute = 1)
 ```
 
 Functions in `datefixR` assume day-first instead of month-first when day, month,
-and year are all given (unless year is given first). However this behaviour can
+and year are all given (unless year is given first). However this behavior can
 be modified by passing `format = "mdy"` to function calls.  
 
 ### Limitations
diff --git a/README.md b/README.md
index c64f931..882e007 100644
--- a/README.md
+++ b/README.md
@@ -90,7 +90,7 @@ fix_dates(example.df, "example", month.impute = 1)
 
 Functions in `datefixR` assume day-first instead of month-first when
 day, month, and year are all given (unless year is given first). However
-this behaviour can be modified by passing `format = "mdy"` to function
+this behavior can be modified by passing `format = "mdy"` to function
 calls.
 
 ### Limitations
diff --git a/vignettes/datefixR.Rmd b/vignettes/datefixR.Rmd
index 4e03dfb..51e0246 100644
--- a/vignettes/datefixR.Rmd
+++ b/vignettes/datefixR.Rmd
@@ -83,7 +83,7 @@ fix_date("01 02 2014")
 ```
 
 Functions in `datefixR` assume day-first instead of month-first when day, month,
-and year are all given (unless year is given first). However this behaviour can
+and year are all given (unless year is given first). However this behavior can
 be modified by passing `format = "mdy"` to function calls.