Index: runtime.c
===================================================================
--- runtime.c	(revision 15090)
+++ runtime.c	(working copy)
@@ -5382,7 +5382,7 @@
 
 C_regparm C_word C_fcall C_a_i_abs(C_word **a, int c, C_word x)
 {
-  if(x & C_FIXNUM_BIT) return C_fix(abs(C_unfix(x)));
+  if(x & C_FIXNUM_BIT) return C_fix(labs(C_unfix(x)));
 
   if(C_immediatep(x) || C_block_header(x) != C_FLONUM_TAG)
     barf(C_BAD_ARGUMENT_TYPE_ERROR, "abs", x);
