diff --git a/common/extensions.ino b/common/extensions.ino
index 0f3c5eb..eb19111 100644
--- a/common/extensions.ino
+++ b/common/extensions.ino
@@ -418,7 +418,7 @@ fn_sd_existsp(object *args, object *env)
 /*
    (sd-make-dir path)
    Create a directory on the SD card.
-   This will also create any intermediate directories that don’t already exists;
+   This will also create any intermediate directories that don't already exists;
    e.g. SD.mkdir("a/b/c") will create a, b, and c.
  */
 object *