diff --git a/CMakeLists.txt b/CMakeLists.txt
index 735b469..4b497fa 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -246,7 +246,25 @@ check_cxx_source_compiles(
 	"#include <list> 
 	int main(){std::list<int> l; __typeof__(l.begin()) p=l.begin();}"
 	CPPCMS_HAVE_UNDERSCORE_TYPEOF)
+check_cxx_source_compiles(
+       "#ifndef _FILE_OFFSET_BITS
+	#define _FILE_OFFSET_BITS 64
+	#endif
+	#include <stdio.h>
+	int main()
+	{
+		char is_big[sizeof(off_t) >= 8 ? 1 : -1];
+		fseeko(0,0,0);
+	}"
+	CPPCMS_HAVE_FSEEKO
+)
 
+check_cxx_source_compiles(
+	"#include <stdio.h>
+	int main()
+	{ _fseeki64(0,0,0); }"
+	CPPCMS_HAVE_FSEEKI64
+)
 if(NOT DISABLE_GZIP)
 	find_library(ZLIB NAMES z zdll zlib${ZLIB_SUFFIX} zlib)
 	find_path(ZLIB_INCLUDE_DIR zlib.h)
diff --git a/config.cmake.h b/config.cmake.h
index 215bd43..d006ef7 100644
--- a/config.cmake.h
+++ b/config.cmake.h
@@ -110,6 +110,8 @@
 #cmakedefine CPPCMS_NO_GZIP
 #cmakedefine CPPCMS_SQLITE_LINK_STATIC
 #cmakedefine CPPCMS_HAS_THREAD_PSHARED
+#cmakedefine CPPCMS_HAVE_FSEEKI64
+#cmakedefine CPPCMS_HAVE_FSEEKO
 
 
 #endif
diff --git a/private/http_file_buffer.h b/private/http_file_buffer.h
index e6bffde..0e50ce4 100644
--- a/private/http_file_buffer.h
+++ b/private/http_file_buffer.h
@@ -10,10 +10,14 @@
 #ifndef _FILE_OFFSET_BITS
 #define _FILE_OFFSET_BITS 64
 #endif
-
-#ifdef CPPCMS_WIN_NATIVE
+#include <cppcms/config.h>
+#include <stdlib.h>
+#ifdef CPPCMS_HAVE_FSEEKO
+// nothing
+#elif defined(CPPCMS_HAVE_FSEEKI64)
 #define fseeko(f,o,w) _fseeki64(f,o,w)
-#define ftello(f) _ftelli64(f)
+#else
+#define fseek(f,o,w) fseek(f,o,w)
 #endif
 
 #include <booster/nowide/cstdio.h>
diff --git a/tests/file_buffer_test.cpp b/tests/file_buffer_test.cpp
index b87c326..27a5b9d 100644
--- a/tests/file_buffer_test.cpp
+++ b/tests/file_buffer_test.cpp
@@ -131,8 +131,6 @@ int main()
 				test(size,inmem[m]);
 			}
 		}
-		FILE *f=0;
-		TEST(sizeof( ftello(f) ) > 4);
 	}
 	catch(std::exception const &e) {
 		std::cerr << "FAIL: " << e.what() << std::endl;