diff --git a/cmd/img_mgmt/include/img_mgmt/img_mgmt_config.h b/cmd/img_mgmt/include/img_mgmt/img_mgmt_config.h
index ee0343a..e24e44c 100644
--- a/cmd/img_mgmt/include/img_mgmt/img_mgmt_config.h
+++ b/cmd/img_mgmt/include/img_mgmt/img_mgmt_config.h
@@ -46,9 +46,12 @@
 #define IMG_MGMT_UPDATABLE_IMAGE_NUMBER CONFIG_IMG_MGMT_UPDATABLE_IMAGE_NUMBER
 #endif
 
+#else
+
 /* No direct support for this OS.  The application needs to define the above
  * settings itself.
  */
+#error "Unknown OS/missing configuration"
 
 #endif