diff --git a/src/internal/ntux_nolibc_impl.h b/src/internal/ntux_nolibc_impl.h
index f68d282..f87355c 100644
--- a/src/internal/ntux_nolibc_impl.h
+++ b/src/internal/ntux_nolibc_impl.h
@@ -36,6 +36,8 @@ int	ntux_strncmp(const char * a, const char * b, size_t n);
 char *	ntux_strchr(const char * ch, int c);
 char *	ntux_strrchr(const char * ch, int c);
 
+int     ntux_isblank(int c);
+
 void *	ntux_calloc(size_t n, size_t size);
 void	ntux_free(void *);