diff --git a/src/sql/upgrade-84.sql b/src/sql/upgrade-84.sql
new file mode 100644
index 00000000..bf142b30
--- /dev/null
+++ b/src/sql/upgrade-84.sql
@@ -0,0 +1,4 @@
+-- CA derivations do not have statically known output paths. The values
+-- are only filled in after the build runs.
+ALTER TABLE BuildStepOutputs ALTER COLUMN path DROP NOT NULL;
+ALTER TABLE BuildOutputs ALTER COLUMN path DROP NOT NULL;