diff --git a/libs/circle-newlib b/libs/circle-newlib
index 00b404f..584d4c2 160000
--- a/libs/circle-newlib
+++ b/libs/circle-newlib
@@ -1 +1 @@
-Subproject commit 00b404f6a3a7e8719097573520e36bc153f8301c
+Subproject commit 584d4c22e18665d204f4e4169ea29f8e86f6e2ad
diff --git a/samples/05-smoketest/kernel.cpp b/samples/05-smoketest/kernel.cpp
index f70eced..ac35aad 100644
--- a/samples/05-smoketest/kernel.cpp
+++ b/samples/05-smoketest/kernel.cpp
@@ -33,6 +33,7 @@
 #include <string>
 #include <sys/stat.h>
 #include <unistd.h>
+#include <fcntl.h>
 
 using namespace std;
 
@@ -597,7 +598,7 @@ CKernel::IoTest (void)
     }
 
     {
-        Report ("dup () and dup2 () tests");
+        Report ("dup (), dup2 (), fcntl () tests");
 
         int const original_fd = fileno (redirected_stdout);
 
@@ -628,9 +629,19 @@ CKernel::IoTest (void)
         
         assert (fd_copy2 > fd_copy);
 
-        if (write (fd_copy2, dup_text, sizeof (dup_text) - 1) == -1)
+        int const fd_copy3 = fcntl (fd_copy2, F_DUPFD, 0);
+
+        if (fd_copy3 == -1)
+        {
+            PErrorExit ("fcntl () failed");
+        }
+
+        assert (fd_copy3 > fd_copy);
+        assert (fd_copy3 > fd_copy2);
+
+        if (write (fd_copy3, dup_text, sizeof (dup_text) - 1) == -1)
         {
-            PErrorExit ("write () via fd_copy2 failed");
+            PErrorExit ("write () via fd_copy3 failed");
         }
 
         if (close (fd_copy) < 0)
@@ -642,6 +653,11 @@ CKernel::IoTest (void)
         {
             PErrorExit ("close (fd_copy2) failed");
         }
+
+        if (close (fd_copy3) < 0)
+        {
+            PErrorExit ("close (fd_copy3) failed");
+        }
     }
 
     if (fclose (redirected_stdout) != 0)