#ifndef AL_MATH_DEFS_H
#define AL_MATH_DEFS_H

#ifdef HAVE_FLOAT_H
#include <float.h>
#endif

#define F_PI    (3.14159265358979323846f)
#define F_PI_2  (1.57079632679489661923f)
#define F_TAU   (6.28318530717958647692f)

#ifndef FLT_EPSILON
#define FLT_EPSILON (1.19209290e-07f)
#endif

#define DEG2RAD(x)  ((ALfloat)(x) * (F_PI/180.0f))
#define RAD2DEG(x)  ((ALfloat)(x) * (180.0f/F_PI))

#endif /* AL_MATH_DEFS_H */

#ifndef AL_MATH_DEFS_H
#define AL_MATH_DEFS_H

#define F_PI    (3.14159265358979323846f)
#define F_PI_2  (1.57079632679489661923f)
#define F_TAU   (6.28318530717958647692f)

#ifndef FLT_EPSILON
#define FLT_EPSILON (1.19209290e-07f)
#endif

#define DEG2RAD(x)  ((ALfloat)(x) * (F_PI/180.0f))
#define RAD2DEG(x)  ((ALfloat)(x) * (180.0f/F_PI))

#endif /* AL_MATH_DEFS_H */

--- 
+++ 
@@ -1,5 +1,9 @@
 #ifndef AL_MATH_DEFS_H
 #define AL_MATH_DEFS_H
+
+#ifdef HAVE_FLOAT_H
+#include <float.h>
+#endif
 
 #define F_PI    (3.14159265358979323846f)
 #define F_PI_2  (1.57079632679489661923f)
Include float.h if present before defining math stuff
