diff --git a/meta/conf/bitbake.conf b/meta/conf/bitbake.conf
index dd2df8a552..52a36d788b 100644
--- a/meta/conf/bitbake.conf
+++ b/meta/conf/bitbake.conf
@@ -928,7 +928,7 @@ SHELL[unexport] = "1"
 TRANSLATED_TARGET_ARCH ??= "${@d.getVar('TARGET_ARCH').replace("_", "-")}"
 
 # Set a default umask to use for tasks for determinism
-BB_DEFAULT_UMASK = "022"
+BB_DEFAULT_UMASK ??= "022"
 
 # Complete output from bitbake
 BB_CONSOLELOG ?= "${LOG_DIR}/cooker/${MACHINE}/${DATETIME}.log"