diff --git a/cfg/std.cfg b/cfg/std.cfg
index fe8c92150..f6d065fef 100644
--- a/cfg/std.cfg
+++ b/cfg/std.cfg
@@ -1600,6 +1600,7 @@ The obsolete function 'gets' is called. With 'gets' you'll get a buffer overrun
     <pure/>
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int">arg1&gt;=L'0' &amp;&amp; arg1&lt;=L'9'</returnValue>
     <arg nr="1">
       <not-uninit/>
     </arg>
diff --git a/test/cfg/std.c b/test/cfg/std.c
index 20a9125ba..9f67b29e7 100644
--- a/test/cfg/std.c
+++ b/test/cfg/std.c
@@ -3722,6 +3722,11 @@ void valueFlow(void)
     // cppcheck-suppress knownConditionTrueFalse
     AssertAlwaysTrue(iswblank(w0) == 0);
 
+    // cppcheck-suppress knownConditionTrueFalse
+    AssertAlwaysTrue(iswdigit(w0) == 0);
+    // cppcheck-suppress knownConditionTrueFalse
+    AssertAlwaysTrue(iswdigit(wtab) == 1);
+
     // cppcheck-suppress knownConditionTrueFalse
     AssertAlwaysTrue(labs(three) == 3);
     // cppcheck-suppress knownConditionTrueFalse