diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index cdf4aa01e92..4c951678c0a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -343,6 +343,9 @@ AllocateSnapshotBuilder(ReorderBuffer *reorder,
 
 	MemoryContextSwitchTo(oldcontext);
 
+	/* The initial running transactions array must be empty. */
+	Assert(NInitialRunningXacts == 0 && InitialRunningXacts == NULL);
+
 	return builder;
 }
 
@@ -363,6 +366,10 @@ FreeSnapshotBuilder(SnapBuild *builder)
 
 	/* other resources are deallocated via memory context reset */
 	MemoryContextDelete(context);
+
+	/* InitialRunningXacts is freed along with the context */
+	NInitialRunningXacts = 0;
+	InitialRunningXacts = NULL;
 }
 
 /*