diff -ur octave-4.1.0+.orig/liboctave/util/oct-inttypes.cc octave-4.1.0+/liboctave/util/oct-inttypes.cc
--- octave-4.1.0+.orig/liboctave/util/oct-inttypes.cc	2016-06-17 14:01:56.000000000 -0400
+++ octave-4.1.0+/liboctave/util/oct-inttypes.cc	2016-06-17 19:52:03.943017663 -0400
@@ -105,7 +105,31 @@
 
 #if defined (OCTAVE_ENSURE_LONG_DOUBLE_OPERATIONS_ARE_NOT_TRUNCATED)
 
-#define DEFINE_OCTAVE_LONG_DOUBLE_CMP_OP_TEMPLATES(T) \
+typedef unsigned short fpucw_t; /* glibc calls this fpu_control_t */
+
+# define FPU_PC_MASK 0x0300
+# define FPU_PC_DOUBLE 0x200    /* glibc calls this _FPU_DOUBLE */
+# define FPU_PC_EXTENDED 0x300  /* glibc calls this _FPU_EXTENDED */
+
+# define GET_FPUCW() \
+  ({ fpucw_t _cw;                                               \
+     __asm__ __volatile__ ("fnstcw %0" : "=m" (*&_cw));         \
+     _cw;                                                       \
+   })
+# define SET_FPUCW(word) \
+  (void)({ fpucw_t _ncw = (word);                               \
+           __asm__ __volatile__ ("fldcw %0" : : "m" (*&_ncw));  \
+         })
+
+# define DECL_LONG_DOUBLE_ROUNDING \
+  fpucw_t oldcw;
+# define BEGIN_LONG_DOUBLE_ROUNDING() \
+  (void)(oldcw = GET_FPUCW (),                                  \
+         SET_FPUCW ((oldcw & ~FPU_PC_MASK) | FPU_PC_EXTENDED))
+# define END_LONG_DOUBLE_ROUNDING() \
+  SET_FPUCW (oldcw)
+
+#define DEFINE_OCTAVE_LONG_DOUBLE_CMP_OP_TEMPLATES(T)   \
   template <typename xop> \
   bool \
   octave_int_cmp_op::external_mop (double x, T y) \