diff --git a/components/esp_modem/examples/simple_cmux_client/sdkconfig.defaults b/components/esp_modem/examples/simple_cmux_client/sdkconfig.defaults
index 7841f6833..b6fa51455 100644
--- a/components/esp_modem/examples/simple_cmux_client/sdkconfig.defaults
+++ b/components/esp_modem/examples/simple_cmux_client/sdkconfig.defaults
@@ -6,6 +6,7 @@ CONFIG_LWIP_TCPIP_TASK_STACK_SIZE=4096
 CONFIG_LWIP_PPP_ENABLE_IPV6=n
 CONFIG_COMPILER_CXX_EXCEPTIONS=y
 CONFIG_PARTITION_TABLE_TWO_OTA=y
+CONFIG_ESPTOOLPY_FLASHSIZE_4MB=y
 CONFIG_NEWLIB_STDOUT_LINE_ENDING_LF=y
 CONFIG_NEWLIB_STDIN_LINE_ENDING_LF=y
 CONFIG_MAIN_TASK_STACK_SIZE=8192
\ No newline at end of file