diff --git a/resources/sql/patches/026.diffpropkey.sql b/resources/sql/patches/026.diffpropkey.sql
new file mode 100644
index 0000000000..ed12a62f10
--- /dev/null
+++ b/resources/sql/patches/026.diffpropkey.sql
@@ -0,0 +1,3 @@
+ALTER TABLE phabricator_differential.differential_diffproperty
+  ADD UNIQUE KEY (diffID, name);
+