diff --git a/arguments.c b/arguments.c
index fdf43752f..cab40aa6e 100644
--- a/arguments.c
+++ b/arguments.c
@@ -149,7 +149,7 @@ args_parse_flag_argument(struct args_value *values, u_int count, char **cause,
     int optional_argument)
 {
 	struct args_value	*argument, *new;
-	const char		*s;
+	const char		*s, *as;
 
 	new = xcalloc(1, sizeof *new);
 	if (*string != '\0') {
@@ -180,12 +180,24 @@ args_parse_flag_argument(struct args_value *values, u_int count, char **cause,
 		xasprintf(cause, "-%c expects an argument", flag);
 		return (-1);
 	}
+
+	if (optional_argument && argument->type == ARGS_STRING) {
+		as = argument->string;
+		if (as[0] == '-' && (as[1] == '-' || isalpha((u_char)as[1]))) {
+			args_free_value(new);
+			free(new);
+			log_debug("%s: -%c (optional)", __func__, flag);
+			args_set(args, flag, NULL, ARGS_ENTRY_OPTIONAL_VALUE);
+			return (0);
+		}
+	}
 	args_copy_value(new, argument);
 	(*i)++;
 
 out:
 	s = args_value_as_string(new);
 	log_debug("%s: -%c = %s", __func__, flag, s);
+
 	args_set(args, flag, new, 0);
 	return (0);
 }
diff --git a/cmd-resize-pane.c b/cmd-resize-pane.c
index 8e548dc0e..25dd5a217 100644
--- a/cmd-resize-pane.c
+++ b/cmd-resize-pane.c
@@ -18,6 +18,7 @@
 
 #include <sys/types.h>
 
+#include <ctype.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -63,8 +64,7 @@ cmd_resize_pane_exec(struct cmd *self, struct cmdq_item *item)
 	const char		*errstr, *argval;
 	const char		 flags[4] = { 'U', 'D', 'L', 'R' };
 	char			*cause = NULL, flag;
-	u_int			 opposite = 0;
-	int			 adjust, x, y, status;
+	int			 adjust, x, y, status, opposite = 0;
 	long unsigned		 i;
 	struct grid		*gd = wp->base.grid;
 
@@ -147,8 +147,12 @@ cmd_resize_pane_exec(struct cmd *self, struct cmdq_item *item)
 			continue;
 
 		argval = args_get(args, flag);
-		if (argval == NULL)
-			argval = "1";
+		if (argval == NULL) {
+			if (args_count(args) == 0)
+				argval = "1";
+			else
+				argval = args_string(args, 0);
+		}
 
 		adjust = strtonum(argval, INT_MIN, INT_MAX, &errstr);
 		if (errstr != NULL) {