diff --git a/Makefile b/Makefile
index 46d104c..3377b82 100644
--- a/Makefile
+++ b/Makefile
@@ -51,7 +51,6 @@ install: all
 	cp -a libopenlibm.$(SHLIB_EXT)* $(DESTDIR)$(shlibdir)/
 	cp -a libopenlibm.a $(DESTDIR)$(libdir)/
 	cp -a src/openlibm.h $(DESTDIR)$(includedir)/
-	cp -a include/*.h $(DESTDIR)$(includedir)/openlibm/
 ifneq ($(wildcard $(ARCH)/bsd_asm.h),)
 	cp -a $(ARCH)/bsd_asm.h $(DESTDIR)$(includedir)/openlibm/
 endif
diff --git a/src/openlibm.h b/src/openlibm.h
index 11f85cf..ef118a2 100644
--- a/src/openlibm.h
+++ b/src/openlibm.h
@@ -18,8 +18,12 @@
 #define	_MATH_H_
 
 #include <complex.h>
-#include "cdefs-compat.h"
-#include "types-compat.h"
+
+#if (defined(_WIN32) || defined (_MSC_VER)) && !defined(__WIN32__)
+    #define __WIN32__
+#endif
+
+#define __pure2
 
 /*
  * ANSI/POSIX
@@ -253,7 +257,10 @@ cpackl(long double x, long double y)
  * effect of raising floating-point exceptions, so they are not declared
  * as __pure2.  In C99, FENV_ACCESS affects the purity of these functions.
  */
-__BEGIN_DECLS
+
+#if defined(__cplusplus)
+extern "C" {
+#endif
 /*
  * ANSI/POSIX
  */
@@ -571,5 +578,7 @@ long double	tgammal(long double);
 long double	truncl(long double);
 
 #endif /* __ISO_C_VISIBLE >= 1999 */
-__END_DECLS
+#if defined(__cplusplus)
+}
+#endif
 #endif /* !_MATH_H_ */