diff --git a/src/backend/commands/prepare.c b/src/backend/commands/prepare.c
index 34b6410d6a2..6ecc24fdba8 100644
--- a/src/backend/commands/prepare.c
+++ b/src/backend/commands/prepare.c
@@ -159,6 +159,7 @@ ExecuteQuery(ParseState *pstate,
 	EState	   *estate = NULL;
 	Portal		portal;
 	char	   *query_string;
+	CommandTag	commandTag;
 	int			eflags;
 	long		count;
 
@@ -196,6 +197,15 @@ ExecuteQuery(ParseState *pstate,
 	cplan = GetCachedPlan(entry->plansource, paramLI, NULL, NULL);
 	plan_list = cplan->stmt_list;
 
+	/*
+	 * Normally the PlanSource will have a usable commandTag, but if it has an
+	 * empty statement list, then not so much.  Substitute EXECUTE to avoid
+	 * failing because we have no commandTag to report to the client.
+	 */
+	commandTag = entry->plansource->commandTag;
+	if (commandTag == CMDTAG_UNKNOWN)
+		commandTag = CMDTAG_EXECUTE;
+
 	/*
 	 * DO NOT add any logic that could possibly throw an error between
 	 * GetCachedPlan and PortalDefineQuery, or you'll leak the plan refcount.
@@ -203,7 +213,7 @@ ExecuteQuery(ParseState *pstate,
 	PortalDefineQuery(portal,
 					  NULL,
 					  query_string,
-					  entry->plansource->commandTag,
+					  commandTag,
 					  plan_list,
 					  cplan);