diff --git a/proto/caosdb/entity/v1alpha1/main.proto b/proto/caosdb/entity/v1alpha1/main.proto
index 5bcd86045d781e475504ec03b8c588efbf8885ec..605711e0e3378449eed4b44d6cb220b003899d5e 100644
--- a/proto/caosdb/entity/v1alpha1/main.proto
+++ b/proto/caosdb/entity/v1alpha1/main.proto
@@ -384,6 +384,11 @@ enum MessageCode {
 
   // TODO(tf) This property overrides the name.
   MESSAGE_CODE_PROPERTY_WITH_NAME_OVERRIDE = 79;
+
+  // Indicates that this server cannot process this integer value because it is
+  // out of range. The integer range is an implementation detail and thus this
+  // can happen even though the API allows the value.
+  MESSAGE_CODE_INTEGER_VALUE_OUT_OF_RANGE = 80;
 }
 
 // Messages are used by server's or client's to transport *transient*