diff --git a/include/math.h b/include/math.h
index 264fe0f73..a3c8d28ab 100644
--- a/include/math.h
+++ b/include/math.h
@@ -24,7 +24,7 @@ _PROTOTYPE( double cos,   (double _x)					);
 _PROTOTYPE( double cosh,  (double _x)					);
 _PROTOTYPE( double exp,   (double _x)					);
 _PROTOTYPE( double fabs,  (double _x)					);
-_PROTOTYPE( double fabsf, (float _x)					);
+_PROTOTYPE( float fabsf, (float _x)					);
 _PROTOTYPE( double floor, (double _x)					);
 _PROTOTYPE( double fmod,  (double _x, double _y)			);
 _PROTOTYPE( double frexp, (double _x, int *_exp)			);