diff --git a/ChangeLog.m68k b/ChangeLog.m68k
index b16fde2e50..1c8d232365 100644
--- a/ChangeLog.m68k
+++ b/ChangeLog.m68k
@@ -1,5 +1,8 @@
 2010-03-13  Andreas Schwab  <schwab@linux-m68k.org>
 
+	* sysdeps/m68k/m680x0/fpu/bits/mathinline.h (__signbit)
+	(__signbitf, __signbitl): Define.
+
 	* sysdeps/unix/sysv/linux/m68k/sysdep.h (SYSCALL_ERROR_HANDLER):
 	Add variant for USE__THREAD.
 
diff --git a/sysdeps/m68k/m680x0/fpu/bits/mathinline.h b/sysdeps/m68k/m680x0/fpu/bits/mathinline.h
index 6b69f7a493..0da98e40ca 100644
--- a/sysdeps/m68k/m680x0/fpu/bits/mathinline.h
+++ b/sysdeps/m68k/m680x0/fpu/bits/mathinline.h
@@ -1,5 +1,5 @@
 /* Definitions of inline math functions implemented by the m68881/2.
-   Copyright (C) 1991,92,93,94,96,97,98,99,2000,2002, 2003, 2004, 2008
+   Copyright (C) 1991,92,93,94,96,97,98,99,2000,2002, 2003, 2004, 2008, 2010
      Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
@@ -85,6 +85,26 @@
 	       : "=dm" (__result) : "f" (x), "f" (y));	\
       __result != 0; })
 # endif /* GCC 3.1 */
+
+/* Test for negative number.  Used in the signbit() macro.  */
+__MATH_INLINE int
+__NTH (__signbitf (float __x))
+{
+  __extension__ union { float __f; int __i; } __u = { __f: __x };
+  return __u.__i < 0;
+}
+__MATH_INLINE int
+__NTH (__signbit (double __x))
+{
+  __extension__ union { double __d; int __i[2]; } __u = { __d: __x };
+  return __u.__i[0] < 0;
+}
+__MATH_INLINE int
+__NTH (__signbitl (long double __x))
+{
+  __extension__ union { long double __d; int __i[3]; } __u = { __d: __x };
+  return __u.__i[0] < 0;
+}
 #endif