diff --git a/eval.go b/eval.go
index 6a0957c..ec30b2e 100644
--- a/eval.go
+++ b/eval.go
@@ -315,6 +315,11 @@ func (e *setExpr) eval(app *app, args []string) {
 	case "timefmt":
 		gOpts.timefmt = e.val
 	case "truncatechar":
+		if runeSliceWidth([]rune(e.val)) > 1 {
+			app.ui.echoerr("truncatechar: value should be 1 character long")
+			return
+		}
+
 		gOpts.truncatechar = e.val
 	default:
 		app.ui.echoerrf("unknown option: %s", e.opt)