include math.h when testing IEEE

[rrdtool.git] / m4 / acinclude.m4

diff --git a/m4/acinclude.m4 b/m4/acinclude.m4
index f1b6119..c1e5c4b 100644 (file)
--- a/m4/acinclude.m4
+++ b/m4/acinclude.m4
@@ -390,6 +390,10 @@ AC_CACHE_VAL([rd_cv_ieee_$2],
 #  define isinf(a) (fpclassify(a) == FP_INFINITE)
 #endif
 
+#if HAVE_MATH_H
+#include <math.h>
+#endif
+
 #include <stdio.h>
 int main(void){
     double rrdnan,rrdinf,rrdc,rrdzero;