diff --git a/mozilla/Makefile.in b/mozilla/Makefile.in
index 8a166b14f98..603cbb83dab 100644
--- a/mozilla/Makefile.in
+++ b/mozilla/Makefile.in
@@ -163,7 +163,7 @@ ifdef MOZ_SYMBOLS_EXTRA_BUILDID
 EXTRA_BUILDID := -$(MOZ_SYMBOLS_EXTRA_BUILDID)
 endif
 
-SYMBOL_ARCHIVE_BASENAME := \
+SYMBOL_ARCHIVE_BASENAME = \
   $(MOZ_APP_NAME)-$(MOZ_APP_VERSION)-$(OS_ARCH)-$(BUILDID)$(EXTRA_BUILDID)
 
 buildsymbols: