diff --git a/sys/dev/vt/vt_buf.c b/sys/dev/vt/vt_buf.c
--- a/sys/dev/vt/vt_buf.c
+++ b/sys/dev/vt/vt_buf.c
@@ -742,7 +742,7 @@
 	ei = e.tp_row * vb->vb_scr_size.tp_col + e.tp_col;
 
 	/* Number symbols and number of rows to inject \n */
-	sz = ei - si + ((e.tp_row - s.tp_row) * 2);
+	sz = ei - si + (e.tp_row - s.tp_row);
 
 	return (sz * sizeof(term_char_t));
 }
@@ -750,7 +750,7 @@
 void
 vtbuf_extract_marked(struct vt_buf *vb, term_char_t *buf, int sz)
 {
-	int i, r, c, cs, ce;
+	int i, j, r, c, cs, ce;
 	term_pos_t s, e;
 
 	/* Swap according to window coordinates. */
@@ -769,15 +769,29 @@
 	for (r = s.tp_row; r <= e.tp_row; r++) {
 		cs = (r == s.tp_row)?s.tp_col:0;
 		ce = (r == e.tp_row)?e.tp_col:vb->vb_scr_size.tp_col;
-		for (c = cs; c < ce; c++) {
+
+		/* Copy characters from terminal window. */
+		j = i;
+		for (c = cs; c < ce; c++)
 			buf[i++] = vb->vb_rows[r][c];
+
+		/* Trim trailing whitespace from each line, if any. */
+		for (; i != j; i--) {
+			if (TCHAR_CHARACTER(buf[i - 1]) == ' ')
+				buf[i - 1] = '\0';
+			else
+				break;
 		}
+
 		/* Add new line for all rows, but not for last one. */
-		if (r != e.tp_row) {
-			buf[i++] = '\r';
+		if (r != e.tp_row)
 			buf[i++] = '\n';
-		}
 	}
+	/* Zero rest of expected buffer size, if any. */
+	while ((i * sizeof(buf[0])) < sz)
+		buf[i++] = '\0';
+
+	MPASS((i * sizeof(buf[0])) == sz);
 }
 
 int
diff --git a/sys/dev/vt/vt_core.c b/sys/dev/vt/vt_core.c
--- a/sys/dev/vt/vt_core.c
+++ b/sys/dev/vt/vt_core.c
@@ -2287,8 +2287,7 @@
 			VD_PASTEBUFSZ(vd) = len;
 		}
 		/* Request copy/paste buffer data, no more than `len' */
-		vtbuf_extract_marked(&vw->vw_buf, VD_PASTEBUF(vd),
-		    VD_PASTEBUFSZ(vd));
+		vtbuf_extract_marked(&vw->vw_buf, VD_PASTEBUF(vd), len);
 
 		VD_PASTEBUFLEN(vd) = len;