--- a/configure.ac
+++ b/configure.ac
@@ -46,18 +46,18 @@
     CFLAGS="${saved_CFLAGS}"
 fi
 
-AC_MSG_CHECKING([for implicit-function-declaration error flag in $CC])
+AC_MSG_CHECKING([for implicit-function-declaration warning flag in $CC])
 saved_CFLAGS="${CFLAGS}"
-CFLAGS="${CFLAGS} -Werror=implicit-function-declaration"
+CFLAGS="${CFLAGS} -Wimplicit-function-declaration"
 AC_COMPILE_IFELSE([AC_LANG_SOURCE([])],[have_implicit_function_declaration="yes"],[have_implicit_function_declaration="no"])
 AC_MSG_RESULT($have_implicit_function_declaration)
 if test "$have_implicit_function_declaration" = "no" ; then
     CFLAGS="${saved_CFLAGS}"
 fi
 
-AC_MSG_CHECKING([for format error flag in $CC])
+AC_MSG_CHECKING([for format warning flag in $CC])
 saved_CFLAGS="${CFLAGS}"
-CFLAGS="${CFLAGS} -Werror=format"
+CFLAGS="${CFLAGS} -Wformat"
 AC_COMPILE_IFELSE([AC_LANG_SOURCE([])],[have_error_format="yes"],[have_error_format="no"])
 AC_MSG_RESULT($have_error_format)
 if test "$have_error_format" = "no" ; then