diff --git a/maud/src/lib.rs b/maud/src/lib.rs
index d948a77..205227c 100644
--- a/maud/src/lib.rs
+++ b/maud/src/lib.rs
@@ -222,7 +222,7 @@ pub mod rt {
     ///
     /// See <https://github.com/rust-lang/rust/issues/16617>
     #[inline]
-    pub fn write_fmt<T: fmt::String>(w: &mut fmt::Writer, value: T) -> fmt::Result {
+    pub fn write_fmt<T: fmt::Display>(w: &mut fmt::Writer, value: T) -> fmt::Result {
         write!(w, "{}", value)
     }