--- a/acinclude.m4
+++ b/acinclude.m4
@@ -78,7 +78,7 @@
 AC_PATH_TOOL([$1], [$2])
 if test "$DX_FLAG_[]DX_CURRENT_FEATURE$$1" = 1; then
     AC_MSG_WARN([$2 not found - will not DX_CURRENT_DESCRIPTION])
-    AC_SUBST([DX_FLAG_[]DX_CURRENT_FEATURE], 0)
+    AC_SUBST([DX_FLAG_]DX_CURRENT_FEATURE, 0)
 fi
 ])
 
@@ -101,7 +101,7 @@
 # ----------------------------------------------------------
 # Turn off the DX_CURRENT_FEATURE if the required feature is off.
 AC_DEFUN([DX_CLEAR_DEPEND], [
-test "$DX_FLAG_$1" = "$2" || AC_SUBST([DX_FLAG_[]DX_CURRENT_FEATURE], 0)
+test "$DX_FLAG_$1" = "$2" || AC_SUBST([DX_FLAG_]DX_CURRENT_FEATURE, 0)
 ])
 
 # DX_FEATURE_ARG(FEATURE, DESCRIPTION,