diff --git a/libraries/stdlib/test/text/StringBuilderTest.kt b/libraries/stdlib/test/text/StringBuilderTest.kt
index e18b2e3d7b2..b5ed72b20d8 100644
--- a/libraries/stdlib/test/text/StringBuilderTest.kt
+++ b/libraries/stdlib/test/text/StringBuilderTest.kt
@@ -99,7 +99,8 @@ class StringBuilderTest {
             sb.append('\uD800')
             sb.append('\uDC00')
 
-            sb.insert(10, "\uDC01\uD801")
+            sb.insert(10, '\uDC01')
+            sb.insert(11, '\uD801')
             sb.insert(0, "\uD802\uDC02")
 
             sb.reverse()