diff --git a/src/fd/dupable.cpp b/src/fd/dupable.cpp
index d096d04..e9b0982 100644
--- a/src/fd/dupable.cpp
+++ b/src/fd/dupable.cpp
@@ -39,5 +39,10 @@
     return handle.value();
 }
 
+DupableFd::operator bool() const noexcept
+{
+    return static_cast<bool>(handle);
+}
+
 } // namespace fd
 } // namespace stdplus
diff --git a/src/fd/managed.cpp b/src/fd/managed.cpp
index 5669903..b9cfa87 100644
--- a/src/fd/managed.cpp
+++ b/src/fd/managed.cpp
@@ -55,5 +55,10 @@
     return handle.value();
 }
 
+ManagedFd::operator bool() const noexcept
+{
+    return static_cast<bool>(handle);
+}
+
 } // namespace fd
 } // namespace stdplus