diff --git a/qse/lib/awk/StdAwk.cpp b/qse/lib/awk/StdAwk.cpp
index 07db16c3..9e03c747 100644
--- a/qse/lib/awk/StdAwk.cpp
+++ b/qse/lib/awk/StdAwk.cpp
@@ -872,7 +872,14 @@ int StdAwk::open_console_in (Console& io)
 		 */
 		argv = qse_awk_rtx_getgbl (rtx, this->gbl_argv);
 		QSE_ASSERT (argv != QSE_NULL);
-		QSE_ASSERT (QSE_AWK_RTX_GETVALTYPE (rtx, argv) == QSE_AWK_VAL_MAP);
+		if (QSE_AWK_RTX_GETVALTYPE(rtx, argv) != QSE_AWK_VAL_MAP)
+		{
+			/* with FLEXMAP on, you can change ARGV to a scalar.
+			 *   BEGIN { ARGV="xxx"; }
+			 * you must not do this. */
+			qse_awk_rtx_seterrfmt (rtx, QSE_AWK_EINVAL, QSE_NULL, QSE_T("phony value in ARGV"));
+			return -1;
+		}
 
 		map = ((qse_awk_val_map_t*)argv)->map;
 		QSE_ASSERT (map != QSE_NULL);
diff --git a/qse/lib/awk/std.c b/qse/lib/awk/std.c
index ca3dd986..2fd2776b 100644
--- a/qse/lib/awk/std.c
+++ b/qse/lib/awk/std.c
@@ -1658,7 +1658,14 @@ static int open_rio_console (qse_awk_rtx_t* rtx, qse_awk_rio_arg_t* riod)
 			 */
 			argv = qse_awk_rtx_getgbl(rtx, xtn->gbl_argv);
 			QSE_ASSERT (argv != QSE_NULL);
-			QSE_ASSERT (QSE_AWK_RTX_GETVALTYPE (rtx, argv) == QSE_AWK_VAL_MAP);
+			if (QSE_AWK_RTX_GETVALTYPE(rtx, argv) != QSE_AWK_VAL_MAP)
+			{
+				/* with FLEXMAP on, you can change ARGV to a scalar.
+				 *   BEGIN { ARGV="xxx"; }
+				 * you must not do this. */
+				qse_awk_rtx_seterrfmt (rtx, QSE_AWK_EINVAL, QSE_NULL, QSE_T("phony value in ARGV"));
+				return -1;
+			}
 
 			map = ((qse_awk_val_map_t*)argv)->map;
 			QSE_ASSERT (map != QSE_NULL);