diff --git a/source/app.d b/source/app.d
index 86c3297..ae03da5 100644
--- a/source/app.d
+++ b/source/app.d
@@ -1,6 +1,6 @@
 // xasm 3.1.1 by Piotr Fusik <fox@scene.pl>
 // http://xasm.atari.org
-// Can be compiled with DMD v2.092.0.
+// Can be compiled with DMD v2.096.0.
 
 // Poetic License:
 //
@@ -2171,6 +2171,10 @@ void assemblyOpt() {
 		case 'u':
 			optionUnusedLabels = readOption();
 			break;
+		case '?':
+			if (!readOption())
+				throw new AssemblyError("OPT ?- not supported");
+			break;
 		default:
 			column--;
 			return;
diff --git a/xasm.1.asciidoc b/xasm.1.asciidoc
index 4a0f7d4..f660ce7 100644
--- a/xasm.1.asciidoc
+++ b/xasm.1.asciidoc
@@ -304,12 +304,14 @@ Six options are available:
 +
 You can turn any of these on or off.
 The default (if no `OPT` specified) is `opt f-g-h+l+o+u+`.
+For compatibility with MADS, `opt ?+` is accepted and ignored.
 Examples:
 +
 ------------------------------------------------------------------------------
  opt l-     listing off
  opt l+o-   listing on, object file off
  opt f+g+h- useful for Atari 5200 cartridges - raw output, 5200 hw regs
+ opt ?+     MADS compatibility, no effect
 ------------------------------------------------------------------------------
 
 *ORG* - change value of the origin counter::