diff --git a/boot/zephyr/CMakeLists.txt b/boot/zephyr/CMakeLists.txt
index 70a88a7a8..0d3fd27a4 100644
--- a/boot/zephyr/CMakeLists.txt
+++ b/boot/zephyr/CMakeLists.txt
@@ -6,14 +6,6 @@
 
 cmake_minimum_required(VERSION 3.8.2)
 
-# Board-specific CONF_FILES should get merged into the build as well.
-# Default to qemu_x86 if no board has been specified.
-# If BOARD is already defined, mcuboot is being built in a multi image
-# context, and should default to its parent image BOARD.
-if (NOT BOARD)
-  set(BOARD qemu_x86)
-endif()
-
 # Add a common dts overlay necessary to ensure mcuboot is linked into,
 # and fits inside, the boot partition. (If the user specified a
 # DTC_OVERLAY_FILE on the CMake command line, we need to append onto