diff --git a/format.cc b/format.cc
index c592f8ae..03c10e40 100644
--- a/format.cc
+++ b/format.cc
@@ -31,19 +31,9 @@
 #undef _SCL_SECURE_NO_WARNINGS
 #define _SCL_SECURE_NO_WARNINGS
 
-#include <math.h>
-
 #include "format.h"
 
 #include <cctype>
-#include <cstring>
-#include <algorithm>
-
-#if _MSC_VER
-# undef snprintf
-# define snprintf _snprintf
-# define isinf(x) (!_finite(x))
-#endif
 
 const char fmt::internal::DIGITS[] =
     "0001020304050607080910111213141516171819"
diff --git a/format.h b/format.h
index b62356b4..d5971618 100644
--- a/format.h
+++ b/format.h
@@ -181,6 +181,9 @@ inline int SignBit(double value) {
   _ecvt(value, 0, &dec, &sign);
   return sign;
 }
+inline int isinf(double x) { return !_finite(x); }
+# undef snprintf
+# define snprintf _snprintf
 #endif
 
 template <typename Char>