diff --git a/docs/extensiondev.rst b/docs/extensiondev.rst
index 340a18da..77ce7cde 100644
--- a/docs/extensiondev.rst
+++ b/docs/extensiondev.rst
@@ -438,7 +438,7 @@ When writing an extension, you should only use APIs documented at
 at any time and are not something extensions should use.
 
 Mopidy performs type checking to help catch extension bugs. This applies to
-both to frontend calls into core and return values from backends. Additionally
+both frontend calls into core and return values from backends. Additionally
 model fields always get validated to further guard against bad data.
 
 Logging in extensions