diff --git a/ChangeLog b/ChangeLog
index 495f088196..abd8fcbba4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2016-06-14  Joseph Myers  <joseph@codesourcery.com>
+
+	* math/s_fdim.c (__fdim): Use islessequal and isinf instead of
+	fpclassify.
+	* math/s_fdimf.c (__fdimf): Likewise.
+	* math/s_fdiml.c (__fdiml): Likewise.
+
 2016-06-14  Rajalakshmi Srinivasaraghavan  <raji@linux.vnet.ibm.com>
 
 	* sysdeps/powerpc/powerpc64/multiarch/Makefile:
diff --git a/math/s_fdim.c b/math/s_fdim.c
index b02ed27233..8789ca4c38 100644
--- a/math/s_fdim.c
+++ b/math/s_fdim.c
@@ -23,19 +23,11 @@
 double
 __fdim (double x, double y)
 {
-  int clsx = fpclassify (x);
-  int clsy = fpclassify (y);
-
-  if (clsx == FP_NAN || clsy == FP_NAN)
-    /* Raise invalid flag for signaling but not quiet NaN.  */
-    return x - y;
-
-  if (x <= y)
+  if (islessequal (x, y))
     return 0.0;
 
   double r = x - y;
-  if (fpclassify (r) == FP_INFINITE
-      && clsx != FP_INFINITE && clsy != FP_INFINITE)
+  if (isinf (r) && !isinf (x) && !isinf (y))
     __set_errno (ERANGE);
 
   return r;
diff --git a/math/s_fdimf.c b/math/s_fdimf.c
index b905380478..2e8eccfc4f 100644
--- a/math/s_fdimf.c
+++ b/math/s_fdimf.c
@@ -23,19 +23,11 @@
 float
 __fdimf (float x, float y)
 {
-  int clsx = fpclassify (x);
-  int clsy = fpclassify (y);
-
-  if (clsx == FP_NAN || clsy == FP_NAN)
-    /* Raise invalid flag for signaling but not quiet NaN.  */
-    return x - y;
-
-  if (x <= y)
+  if (islessequal (x, y))
     return 0.0f;
 
   float r = x - y;
-  if (fpclassify (r) == FP_INFINITE
-      && clsx != FP_INFINITE && clsy != FP_INFINITE)
+  if (isinf (r) && !isinf (x) && !isinf (y))
     __set_errno (ERANGE);
 
   return r;
diff --git a/math/s_fdiml.c b/math/s_fdiml.c
index df3f1e5ba4..4a1f6722c6 100644
--- a/math/s_fdiml.c
+++ b/math/s_fdiml.c
@@ -23,19 +23,11 @@
 long double
 __fdiml (long double x, long double y)
 {
-  int clsx = fpclassify (x);
-  int clsy = fpclassify (y);
-
-  if (clsx == FP_NAN || clsy == FP_NAN)
-    /* Raise invalid flag for signaling but not quiet NaN.  */
-    return x - y;
-
-  if (x <= y)
+  if (islessequal (x, y))
     return 0.0f;
 
   long double r = x - y;
-  if (fpclassify (r) == FP_INFINITE
-      && clsx != FP_INFINITE && clsy != FP_INFINITE)
+  if (isinf (r) && !isinf (x) && !isinf (y))
     __set_errno (ERANGE);
 
   return r;