diff --git a/models/MarketTransaction.json b/models/MarketTransaction.json
index 08d1367..a89f931 100644
--- a/models/MarketTransaction.json
+++ b/models/MarketTransaction.json
@@ -24,17 +24,17 @@
     "units": {
       "type": "integer",
       "description": "The number of units of the transaction.",
-      "minimum": 1
+      "minimum": 0
     },
     "pricePerUnit": {
       "type": "integer",
       "description": "The price per unit of the transaction.",
-      "minimum": 1
+      "minimum": 0
     },
     "totalPrice": {
       "type": "integer",
       "description": "The total price of the transaction.",
-      "minimum": 1
+      "minimum": 0
     },
     "timestamp": {
       "type": "string",
diff --git a/models/ShipyardTransaction.json b/models/ShipyardTransaction.json
index 877a911..8c09e70 100644
--- a/models/ShipyardTransaction.json
+++ b/models/ShipyardTransaction.json
@@ -12,7 +12,7 @@
     "price": {
       "type": "integer",
       "description": "The price of the transaction.",
-      "minimum": 1
+      "minimum": 0
     },
     "agentSymbol": {
       "type": "string",