diff --git a/clr_loader/util/runtime_spec.py b/clr_loader/util/runtime_spec.py
index 2eaeb68..89bf775 100644
--- a/clr_loader/util/runtime_spec.py
+++ b/clr_loader/util/runtime_spec.py
@@ -18,7 +18,8 @@ def tfm(self) -> str:
 
     @property
     def floor_version(self) -> str:
-        return f"{self.version[:3]}.0"
+        major, minor, _ = self.version.split(".")
+        return f"{major}.{minor}.0"
 
     @property
     def runtime_config(self) -> Dict[str, Any]: