diff --git a/boards/sim/sim/sim/configs/libcxxtest/defconfig b/boards/sim/sim/sim/configs/libcxxtest/defconfig
index ff2156cd035..3929289c0af 100644
--- a/boards/sim/sim/sim/configs/libcxxtest/defconfig
+++ b/boards/sim/sim/sim/configs/libcxxtest/defconfig
@@ -91,3 +91,4 @@ CONFIG_SYSTEM_NSH=y
 CONFIG_SYSTEM_PING=y
 CONFIG_TESTING_CXXTEST=y
 CONFIG_TLS_NELEM=4
+CONFIG_TLS_TASK_NELEM=8