diff --git a/engines/lastexpress/entities/gendarmes.cpp b/engines/lastexpress/entities/gendarmes.cpp
index 5ecf8ef804f..b628b8dfe70 100644
--- a/engines/lastexpress/entities/gendarmes.cpp
+++ b/engines/lastexpress/entities/gendarmes.cpp
@@ -169,6 +169,9 @@ IMPLEMENT_FUNCTION_IISS(9, Gendarmes, doCompartment, CarIndex, EntityPosition)
 			strcpy((char *)&parameters1->seq3, "632F");
 		}
 
+		// The sequence 3 string needs to be a maximum of 9 characters, leaving 5 characters after the initial setup
+		assert(Common::String(params->seq1).size() <= 5);
+
 		strcat((char *)&parameters1->seq1, (char *)&params->seq1);
 		strcat((char *)&parameters1->seq2, (char *)&params->seq1);
 		strcat((char *)&parameters1->seq3, (char *)&params->seq1);