diff --git a/Zend/zend_portability.h b/Zend/zend_portability.h
index 546a66b9f5675..c626ad75e2478 100644
--- a/Zend/zend_portability.h
+++ b/Zend/zend_portability.h
@@ -442,6 +442,20 @@ char *alloca();
 
 #define ZEND_NAN NAN
 
+#if defined(__cplusplus) && __cplusplus >= 201103L
+	extern "C++" {
+# include <cmath>
+# define zend_isnan std::isnan
+# define zend_isinf std::isinf
+# define zend_finite std::isfinite
+	}
+#else
+# include <math.h>
+# define zend_isnan(a) isnan(a)
+# define zend_isinf(a) isinf(a)
+# define zend_finite(a) isfinite(a)
+#endif
+
 #define ZEND_STRL(str)		(str), (sizeof(str)-1)
 #define ZEND_STRS(str)		(str), (sizeof(str))
 #define ZEND_NORMALIZE_BOOL(n)			\
diff --git a/configure.ac b/configure.ac
index 2af5c49809083..da1b11f84f3eb 100644
--- a/configure.ac
+++ b/configure.ac
@@ -61,21 +61,6 @@ AH_BOTTOM([
 
 #include <string.h>
 
-#if defined(__cplusplus) && __cplusplus >= 201103L
-extern "C++" {
-#include <cmath>
-#define zend_isnan std::isnan
-#define zend_isinf std::isinf
-#define zend_finite std::isfinite
-}
-#else
-#include <math.h>
-
-#define zend_isnan(a) isnan(a)
-#define zend_isinf(a) isinf(a)
-#define zend_finite(a) isfinite(a)
-
-#endif
 #endif /* ifndef ZEND_ACCONFIG_H_NO_C_PROTOS */
 
 #endif /* PHP_CONFIG_H */