diff --git a/config/Config-kernel.in b/config/Config-kernel.in
index 2a0ba91cd..d5bdf762a 100644
--- a/config/Config-kernel.in
+++ b/config/Config-kernel.in
@@ -817,7 +817,7 @@ config KERNEL_SQUASHFS_FRAGMENT_CACHE_SIZE
 #
 choice
 	prompt "Compiler optimization level"
-	default KERNEL_CC_OPTIMIZE_FOR_PERFORMANCE
+	default KERNEL_CC_OPTIMIZE_FOR_SIZE if SMALL_FLASH
 
 config KERNEL_CC_OPTIMIZE_FOR_PERFORMANCE
 	bool "Optimize for performance"