diff --git a/build/makefile_base.mak b/build/makefile_base.mak
index 313257ef..6c14f34a 100644
--- a/build/makefile_base.mak
+++ b/build/makefile_base.mak
@@ -25,6 +25,14 @@ else # (Rest of the file is the else)
 ## Config
 ##
 
+# We expect the configure script to conditionally set the following:
+#   SRCDIR          - Path to source
+#   NO_DXVK         - 1 if skipping DXVK steps
+#   STEAMRT64_MODE  - 'docker' or '' for automatic Steam Runtime container
+#   STEAMRT64_IMAGE - Name of the image if mode is set
+#   STEAMRT32_MODE  - Same as above for 32-bit container (can be different type)
+#   STEAMRT32_IMAGE - Same as above for 32-bit container
+
 ifeq ($(SRCDIR),)
 	foo := $(error SRCDIR not set, do not include makefile_base directly, run ./configure.sh to generate Makefile)
 endif