diff --git a/src/fd/ops.cpp b/src/fd/ops.cpp
index d05e9b2..ca549f7 100644
--- a/src/fd/ops.cpp
+++ b/src/fd/ops.cpp
@@ -226,6 +226,14 @@
     }
 }
 
+void verifyExact(size_t expected, size_t actual)
+{
+    if (expected != actual)
+    {
+        throw exception::WouldBlock("verifyExact");
+    }
+}
+
 } // namespace detail
 } // namespace fd
 } // namespace stdplus