--- popt/configure.ac
+++ popt/configure.ac
@@ -42,7 +42,6 @@ AC_GCC_TRADITIONAL
 AC_SYS_LARGEFILE
 
 AC_ISC_POSIX
-AM_C_PROTOTYPES
 AC_CHECK_VA_COPY
 
 AC_CHECK_HEADERS(float.h glob.h langinfo.h libintl.h mcheck.h unistd.h)