diff --git a/x/logic/predicate/string.go b/x/logic/predicate/string.go
index 8046ca054..c63653f7a 100644
--- a/x/logic/predicate/string.go
+++ b/x/logic/predicate/string.go
@@ -44,7 +44,7 @@ import (
 //	String = 'Hello World'
 //	Length = 11
 //
-// ```
+// ```.
 func ReadString(vm *engine.VM, stream, length, result engine.Term, cont engine.Cont, env *engine.Env) *engine.Promise {
 	return engine.Delay(func(ctx context.Context) *engine.Promise {
 		var s *engine.Stream