diff --git a/SRC/plugins/configure.ac b/SRC/plugins/configure.ac
index 3c0cf4f..f67666c 100644
--- a/SRC/plugins/configure.ac
+++ b/SRC/plugins/configure.ac
@@ -5,10 +5,10 @@ AM_INIT_AUTOMAKE(foreign)
 dnl TODO: write a XML-RPC plugin for Adamsnames' interface. See a first version in contrib/
 AC_ARG_ENABLE(plugin,
 [  --enable-plugin=LIST  Build only the following plugins],
-[if test "$enableval" == "no"; then
+[if test "$enableval" = "no"; then
    AC_MSG_ERROR([You cannot disable plugin support])
 else
-   if test "$enableval" == "yes"; then
+   if test "$enableval" = "yes"; then
       AC_MSG_ERROR([You must indicate a list of plugins with this option])
    else
       plugins=$enableval