diff --git a/test/function_input_iterator_test.cpp b/test/function_input_iterator_test.cpp
index 5c151c4..2574673 100644
--- a/test/function_input_iterator_test.cpp
+++ b/test/function_input_iterator_test.cpp
@@ -85,7 +85,7 @@ int main()
         back_inserter(generated)
         );
 
-    BOOST_TEST_EQ(generated.size(), 10);
+    BOOST_TEST_EQ(generated.size(), 10u);
     BOOST_TEST_EQ(counter_generator.n, 42 + 10);
     for(std::size_t i = 0; i != 10; ++i)
         BOOST_TEST_EQ(generated[i], static_cast<int>(42 + i));