diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 05f9f417..a5bf84ed 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -236,7 +236,7 @@ See [How to open the Javascript Console in different browsers](https://webmaster
 5. **Test your changes thoroughly**. That also means testing with usage
    scenarios you don't normally use, e.g. if you only use access control, test
    without and vice versa. If you only test with your printer, test with the
-   virtual printer and vice versa. State in your pull request how your tested
+   virtual printer and vice versa. State in your pull request how you tested
    your changes. Ideally **add unit tests** - OctoPrint severely lacks in that
    department, but we are trying to change that, so any new code already covered
    with a test suite helps a lot!
diff --git a/src/octoprint/printer/__init__.py b/src/octoprint/printer/__init__.py
index 9af47cd9..28a3e888 100644
--- a/src/octoprint/printer/__init__.py
+++ b/src/octoprint/printer/__init__.py
@@ -458,7 +458,7 @@ class PrinterCallback(object):
 		"""
 		Called when the internal state of the :class:`PrinterInterface` changes, due to changes in the printer state,
 		temperatures, log lines, job progress etc. Updates via this method are guaranteed to be throttled to a maximum
-		of 2 callees per second.
+		of 2 calls per second.
 
 		``data`` is a ``dict`` of the following structure::