diff --git a/docs/markdown/Reference-manual.md b/docs/markdown/Reference-manual.md
index 1e0a11cc3..3d4379adf 100644
--- a/docs/markdown/Reference-manual.md
+++ b/docs/markdown/Reference-manual.md
@@ -1109,8 +1109,8 @@ This function prints its argument to stdout prefixed with WARNING:.
 The first argument to this function must be a string defining the name
 of this project. It is followed by programming languages that the
 project uses. Supported values for languages are `c`, `cpp` (for
-`C++`), `d`, `objc`, `objcpp`, `fortran`, `java`, `cs` (for `C#`) and
-`vala`. In versions before `0.40.0` you must have at least one
+`C++`), `d`, `objc`, `objcpp`, `fortran`, `java`, `cs` (for `C#`),
+`vala` and `rust`. In versions before `0.40.0` you must have at least one
 language listed.
 
 The project name can be any string you want, it's not used for