diff --git a/configure.ac b/configure.ac
index 1540ce4b..59275554 100644
--- a/configure.ac
+++ b/configure.ac
@@ -76,7 +76,11 @@ AC_ARG_ENABLE(pie,
 
 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])])
+[
+  AS_IF([test "x$enableval" = "xyes"], [
+    AC_DEFINE([USE_BLOCKING_RANDOM], [1], [Use blocking random])
+  ])
+])
 
 AC_ARG_WITH(safecode,
 [AS_HELP_STRING(--with-safecode,For maintainers only - please do not use)],
@@ -92,18 +96,20 @@ AC_ARG_WITH(safecode,
 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"
+  AS_IF([test "x$enableval" = "xyes"], [
+    AS_IF([test "x$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="$CPPFLAGS -DDEBUG=1"
   ])
-  CPPFLAGS="$CPPFLAGS -DDEBUG=1"
 ])
 
 AC_SUBST([MAINT])