--- a/configure.ac
+++ b/configure.ac
@@ -35,6 +35,11 @@
 dnl C99 support is required to define LLONG_MAX (at least on CentOS 5.7)
 AC_PROG_CC_C99
 
+dnl mkdir_p / MKDIR_P
+AC_PROG_MKDIR_P
+mkdir_p="$MKDIR_P"
+AC_SUBST(mkdir_p)
+
 # Report more warnings to improve code quality.
 CFLAGS="${CFLAGS} -Wall"
 
@@ -50,23 +55,23 @@
 # Don't compare signs as it is a mess
 CFLAGS="${CFLAGS} -Wno-sign-compare"
 
-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($have_implicit_function_declaration)
 AS_IF([test "$have_implicit_function_declaration" = "no"],[CFLAGS="${saved_CFLAGS}"])
 
-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($have_error_format)
 AS_IF([test "$have_error_format" = "no"],[CFLAGS="${saved_CFLAGS}"])
 
 case "$host" in
    *-solaris*)
-   LDFLAGS="${LDFLAGS} -lsocket -lnsl"
+   LIBS="${LIBS} -lsocket -lnsl"
    CFLAGS="-DSOLARIS ${CFLAGS}"
    ;;
 esac