diff --git a/mkosi.conf b/mkosi.conf
index d611635ce7..19a3851fd1 100644
--- a/mkosi.conf
+++ b/mkosi.conf
@@ -15,6 +15,7 @@ Environment=ASAN_OPTIONS=verify_asan_link_order=false
             MKOSI_ASAN_OPTIONS=strict_string_checks=1:detect_stack_use_after_return=1:check_initialization_order=1:strict_init_order=1:disable_coredump=0:use_madv_dontdump=1
             MKOSI_UBSAN_OPTIONS=print_stacktrace=1:print_summary=1:halt_on_error=1
 @SELinuxRelabel=no
+BuildSourcesEphemeral=yes
 
 [Host]
 @Incremental=yes