diff --git a/system/include/libc/math.h b/system/include/libc/math.h
index 3bd0621c2..e9af660fa 100644
--- a/system/include/libc/math.h
+++ b/system/include/libc/math.h
@@ -202,10 +202,18 @@ extern int __signbitd (double x);
   #define isinf(y) (fpclassify(y) == FP_INFINITE)
 #endif
 
+#ifndef isinff
+  #define isinff isinf
+#endif
+
 #ifndef isnan
   #define isnan(y) (fpclassify(y) == FP_NAN)
 #endif
 
+#ifndef isnanf
+  #define isnanf isnan
+#endif
+
 #define isnormal(y) (fpclassify(y) == FP_NORMAL)
 #define signbit(__x) \
 	((sizeof(__x) == sizeof(float))  ?  __signbitf(__x) : \