diff --git a/schema.sql b/schema.sql
index ebc2942..7e0bc30 100644
--- a/schema.sql
+++ b/schema.sql
@@ -134,5 +134,6 @@ CREATE TABLE IF NOT EXISTS inventory (
 	location INTEGER,
 	quantity INTEGER NOT NULL,
 	FOREIGN KEY (part) REFERENCES part (id),
-	FOREIGN KEY (location) REFERENCES location (id)
+	FOREIGN KEY (location) REFERENCES location (id),
+	UNIQUE (part, location)
 );