diff --git a/subsys/shell/backends/Kconfig.backends b/subsys/shell/backends/Kconfig.backends
index 47f82654e6c..2b2e91e2165 100644
--- a/subsys/shell/backends/Kconfig.backends
+++ b/subsys/shell/backends/Kconfig.backends
@@ -398,6 +398,7 @@ config SHELL_PROMPT_DUMMY
 
 config SHELL_BACKEND_DUMMY_BUF_SIZE
 	int "Size of dummy buffer size"
+	default 400 if LOG_PRINTK
 	default 300
 	help
 	  This is size of output buffer that will be used by dummy backend, this limits number of