diff --git a/libgfortran/ChangeLog b/libgfortran/ChangeLog
index ccf5dec226af..9eaa989c0631 100644
--- a/libgfortran/ChangeLog
+++ b/libgfortran/ChangeLog
@@ -1,3 +1,10 @@
+2006-01-12  Roger Sayle  <roger@eyesopen.com>
+
+	* intrinsics/c99_functions.c: Add function prototypes to avoid
+	warnings from -Wstrict-prototypes -Wmissing-prototypes.  On Tru64
+	work around a brain-dead libm by redirecting calls to cabs{,f,l}
+	to a local __gfc_cabs{,f,l}.
+
 2006-01-07  Janne Blomqvist  <jb@gcc.gnu.org>
 
 	* configure.ac: Remove check for sys/mman.h.
diff --git a/libgfortran/intrinsics/c99_functions.c b/libgfortran/intrinsics/c99_functions.c
index 5e93e4279b27..feb4c08b4791 100644
--- a/libgfortran/intrinsics/c99_functions.c
+++ b/libgfortran/intrinsics/c99_functions.c
@@ -35,6 +35,33 @@ Boston, MA 02110-1301, USA.  */
 #define C99_PROTOS_H WE_DONT_WANT_PROTOS_NOW
 #include "libgfortran.h"
 
+/* Tru64's <math.h> declares a non-C99 compliant implementation of cabs,
+   which takes two floating point arguments instead of a single complex.
+   To work around this we redirect cabs{,f,l} calls to __gfc_cabs{,f,l}.  */
+
+#ifdef __osf__
+#undef HAVE_CABS
+#undef HAVE_CABSF
+#undef HAVE_CABSL
+#define cabs __gfc_cabs
+#define cabsf __gfc_cabsf
+#define cabsl __gfc_cabsl
+#endif
+
+/* Prototypes to silence -Wstrict-prototypes -Wmissing-prototypes.  */
+
+float cabsf(float complex);
+double cabs(double complex);
+long double cabsl(long double complex);
+
+float cargf(float complex);
+double carg(double complex);
+long double cargl(long double complex);
+
+float complex clog10f(float complex);
+double complex clog10(double complex);
+long double complex clog10l(long double complex);
+
 
 #ifndef HAVE_ACOSF
 #define HAVE_ACOSF 1