diff --git a/test/input.output/iostream.format/input.streams/istream.unformatted/readsome.pass.cpp b/test/input.output/iostream.format/input.streams/istream.unformatted/readsome.pass.cpp
index fe853d3a..01eecb5d 100644
--- a/test/input.output/iostream.format/input.streams/istream.unformatted/readsome.pass.cpp
+++ b/test/input.output/iostream.format/input.streams/istream.unformatted/readsome.pass.cpp
@@ -59,6 +59,7 @@ int main()
         assert(!is.fail());
         assert(is.gcount() == 1);
         assert(std::string(s, 1) == "0");
+        assert(is.readsome(s, 5) == 0);
     }
     {
         testbuf<wchar_t> sb(L" 1234567890");
@@ -79,5 +80,6 @@ int main()
         assert(!is.fail());
         assert(is.gcount() == 1);
         assert(std::wstring(s, 1) == L"0");
+        assert(is.readsome(s, 5) == 0);
     }
 }