diff --git a/boards/sim/sim/sim/configs/libcxxtest/defconfig b/boards/sim/sim/sim/configs/libcxxtest/defconfig
index f21baaa250..decb4433bd 100644
--- a/boards/sim/sim/sim/configs/libcxxtest/defconfig
+++ b/boards/sim/sim/sim/configs/libcxxtest/defconfig
@@ -10,6 +10,7 @@ CONFIG_ARCH="sim"
 CONFIG_ARCH_BOARD="sim"
 CONFIG_ARCH_BOARD_SIM=y
 CONFIG_ARCH_CHIP="sim"
+CONFIG_ARCH_MATH_H=y
 CONFIG_ARCH_SIM=y
 CONFIG_BOARDCTL_APP_SYMTAB=y
 CONFIG_BOARDCTL_POWEROFF=y