1 files changed, 6 insertions, 4 deletions
diff --git a/missing.h b/missing.h
index 5b4dcc2747..1b9ca2e20b 100644
--- a/missing.h
+++ b/missing.h
@@ -62,11 +62,13 @@ extern double erf(double);
 extern double erfc(double);
 #endif
 
-#ifndef HAVE_ISINF
-# if defined(HAVE_FINITE) && defined(HAVE_ISNAN)
-# define isinf(x) (!finite(x) && !isnan(x))
-# else
+#ifndef isinf
+# ifndef HAVE_ISINF
+#  if defined(HAVE_FINITE) && defined(HAVE_ISNAN)
+#  define isinf(x) (!finite(x) && !isnan(x))
+#  else
 extern int isinf(double);
+#  endif
 # endif
 #endif