diff --git a/lib/libc/include/fpmath.h b/lib/libc/include/fpmath.h
index d5c59d752bc1..ce935eb403e2 100644
--- a/lib/libc/include/fpmath.h
+++ b/lib/libc/include/fpmath.h
@@ -29,6 +29,9 @@
  * $FreeBSD$
  */
 
+#ifndef _FPMATH_H_
+#define _FPMATH_H_
+
 #include <sys/endian.h>
 #include "_fpmath.h"
 
@@ -75,3 +78,5 @@ union IEEEd2bits {
 #endif
 	} bits;
 };
+
+#endif /* !_FPMATH_H */