diff --git a/include/math.h b/include/math.h
index d732648..ffde3da 100644
--- a/include/math.h
+++ b/include/math.h
@@ -44,8 +44,13 @@ int __fpclassifyl(long double);
 union __float_repr { float __f; __uint32_t __i; };
 union __double_repr { double __f; __uint64_t __i; };
 
+#if __STDC_VERSION__ >= 199901L
 #define __FLOAT_BITS(f) (((union __float_repr){ (float)(f) }).__i)
 #define __DOUBLE_BITS(f) (((union __double_repr){ (double)(f) }).__i)
+#else
+static __uint32_t __FLOAT_BITS(float __f) { union __float_repr __u = {__f}; return __u.__i; }
+static __uint64_t __DOUBLE_BITS(double __f) { union __double_repr __u = {__f}; return __u.__i; }
+#endif
 
 #define fpclassify(x) ( \
 	sizeof(x) == sizeof(float) ? __fpclassifyf(x) : \
@@ -199,8 +204,8 @@ float       fmodf(float, float);
 long double fmodl(long double, long double);
 
 double      frexp(double, int *);
-float       frexpf(float value, int *);
-long double frexpl(long double value, int *);
+float       frexpf(float, int *);
+long double frexpl(long double, int *);
 
 double      hypot(double, double);
 float       hypotf(float, float);