diff --git a/configure.ac b/configure.ac
index 2ef9a64b..b811ba5a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -178,9 +178,22 @@ AC_ARG_ENABLE(blocking-random,
 [AS_HELP_STRING(--enable-blocking-random,Use /dev/random instead of /dev/urandom)],
 [AC_DEFINE([USE_BLOCKING_RANDOM], [1], [Use blocking random])])
 
-AC_ARG_ENABLE(blocking-random,
-[AS_HELP_STRING(--enable-blocking-random,Use /dev/random instead of /dev/urandom)],
-[AC_DEFINE([USE_BLOCKING_RANDOM], [1], [Use blocking random])])
+AC_ARG_ENABLE(debug,
+[AS_HELP_STRING(--enable-debug,For maintainers only - please do not use)],
+[
+  AS_IF([test "x$LX_CFLAGS" = "xNONE"], [
+    nxflags=""
+    for flag in `echo $CFLAGS`; do
+      case "$flag" in
+        -O*) ;;
+        -g*) ;;
+        *) AS_VAR_APPEND([nxflags], [" $flag"]) ;;
+      esac
+    done
+    CFLAGS="$nxflags -O0 -g3"
+  ])
+  CPPFLAGS="$CPPFLAGS -DDEBUG=1"
+])
 
 AC_ARG_WITH(safecode,
 [AS_HELP_STRING(--with-safecode,For maintainers only - please do not use)],