diff --git a/configs/sim/cxxtest/defconfig b/configs/sim/cxxtest/defconfig
index d7f5efff5b8..20d4e5c853c 100644
--- a/configs/sim/cxxtest/defconfig
+++ b/configs/sim/cxxtest/defconfig
@@ -279,6 +279,9 @@ CONFIG_LIB_SENDFILE_BUFSIZE=512
 CONFIG_HAVE_CXX=y
 # CONFIG_HAVE_CXXINITIALIZE is not set
 # CONFIG_CXX_NEWLONG is not set
+CONFIG_UCLIBCXX=y
+CONFIG_UCLIBCXX_EXCEPTION=y
+CONFIG_UCLIBCXX_IOSTREAM_BUFSIZE=32
 
 #
 # Application Configuration