--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,8 @@
 2007-10-04  Bruno Haible  <bruno@clisp.org>
 
+	* modules/truncf-tests: New file.
+	* tests/test-truncf.c: New file.
+
 	* modules/truncf: New file.
 	* lib/trunc.c: Make paramerizable through USE_* macros.
 	* lib/truncf.c: New file.

new file mode 100644
--- /dev/null
+++ b/modules/truncf-tests
@@ -0,0 +1,14 @@
+Files:
+tests/test-truncf.c
+
+Depends-on:
+
+configure.ac:
+
+Makefile.am:
+TESTS += test-truncf
+check_PROGRAMS += test-truncf
+test_truncf_LDADD = $(LDADD) @TRUNCF_LIBM@
+
+License:
+LGPL

new file mode 100644
--- /dev/null
+++ b/tests/test-truncf.c
@@ -0,0 +1,83 @@
+/* Test of rounding towards zero.
+   Copyright (C) 2007 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2007.  */
+
+#include <config.h>
+
+#include <math.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#define ASSERT(expr) \
+  do									     \
+    {									     \
+      if (!(expr))							     \
+        {								     \
+          fprintf (stderr, "%s:%d: assertion failed\n", __FILE__, __LINE__); \
+          abort ();							     \
+        }								     \
+    }									     \
+  while (0)
+
+/* The Compaq (ex-DEC) C 6.4 compiler chokes on the expression 0.0 / 0.0.  */
+#ifdef __DECC
+static float
+NaN ()
+{
+  static float zero = 0.0f;
+  return zero / zero;
+}
+#else
+# define NaN() (0.0f / 0.0f)
+#endif
+
+int
+main ()
+{
+  /* Zero.  */
+  ASSERT (truncf (0.0f) == 0.0f);
+  ASSERT (truncf (-0.0f) == 0.0f);
+  /* Positive numbers.  */
+  ASSERT (truncf (0.3f) == 0.0f);
+  ASSERT (truncf (0.7f) == 0.0f);
+  ASSERT (truncf (1.0f) == 1.0f);
+  ASSERT (truncf (1.5f) == 1.0f);
+  ASSERT (truncf (1.999f) == 1.0f);
+  ASSERT (truncf (2.0f) == 2.0f);
+  ASSERT (truncf (65535.99f) == 65535.0f);
+  ASSERT (truncf (65536.0f) == 65536.0f);
+  ASSERT (truncf (2.341e31f) == 2.341e31f);
+  /* Negative numbers.  */
+  ASSERT (truncf (-0.3f) == 0.0f);
+  ASSERT (truncf (-0.7f) == 0.0f);
+  ASSERT (truncf (-1.0f) == -1.0f);
+  ASSERT (truncf (-1.5f) == -1.0f);
+  ASSERT (truncf (-1.999f) == -1.0f);
+  ASSERT (truncf (-2.0f) == -2.0f);
+  ASSERT (truncf (-65535.99f) == -65535.0f);
+  ASSERT (truncf (-65536.0f) == -65536.0f);
+  ASSERT (truncf (-2.341e31f) == -2.341e31f);
+  /* Infinite numbers.  */
+  ASSERT (truncf (1.0f / 0.0f) == 1.0f / 0.0f);
+  ASSERT (truncf (-1.0f / 0.0f) == -1.0f / 0.0f);
+  /* NaNs.  */
+  ASSERT (isnan (truncf (NaN ())));
+
+  return 0;
+}