diff --git a/CHANGELOG.md b/CHANGELOG.md
index 816a64128..9ada31eb9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@
 ### Fixed
 
 - More permissive collection extent deserialization ([#1559](https://github.com/stac-utils/pystac/pull/1559))
+- Type of `proj:code` setter ([#1560](https://github.com/stac-utils/pystac/pull/1560))
 
 ## [v1.13.0] - 2025-04-15
 
diff --git a/pystac/extensions/projection.py b/pystac/extensions/projection.py
index 77adf4e53..4adf3dae2 100644
--- a/pystac/extensions/projection.py
+++ b/pystac/extensions/projection.py
@@ -163,7 +163,7 @@ def code(self) -> str | None:
         return self._get_property(CODE_PROP, str)
 
     @code.setter
-    def code(self, v: int | None) -> None:
+    def code(self, v: str | None) -> None:
         self._set_property(CODE_PROP, v, pop_if_none=False)
 
     @property