diff --git a/src/interfaces/libpq/fe-protocol2.c b/src/interfaces/libpq/fe-protocol2.c
index cf765bee4fa..48023ef2bee 100644
--- a/src/interfaces/libpq/fe-protocol2.c
+++ b/src/interfaces/libpq/fe-protocol2.c
@@ -967,6 +967,14 @@ pqGetErrorNotice2(PGconn *conn, bool isError)
 	char	   *startp;
 	char	   *splitp;
 
+	/*
+	 * If this is an error message, pre-emptively clear any incomplete query
+	 * result we may have.  We'd just throw it away below anyway, and
+	 * releasing it before collecting the error might avoid out-of-memory.
+	 */
+	if (isError)
+		pqClearAsyncResult(conn);
+
 	/*
 	 * Since the message might be pretty long, we create a temporary
 	 * PQExpBuffer rather than using conn->workBuffer.  workBuffer is intended
@@ -1039,7 +1047,7 @@ pqGetErrorNotice2(PGconn *conn, bool isError)
 	 */
 	if (isError)
 	{
-		pqClearAsyncResult(conn);
+		pqClearAsyncResult(conn);	/* redundant, but be safe */
 		conn->result = res;
 		resetPQExpBuffer(&conn->errorMessage);
 		if (res && !PQExpBufferDataBroken(workBuf) && res->errMsg)
diff --git a/src/interfaces/libpq/fe-protocol3.c b/src/interfaces/libpq/fe-protocol3.c
index 547934826ed..280b7145895 100644
--- a/src/interfaces/libpq/fe-protocol3.c
+++ b/src/interfaces/libpq/fe-protocol3.c
@@ -869,6 +869,14 @@ pqGetErrorNotice3(PGconn *conn, bool isError)
 	const char *querytext = NULL;
 	int			querypos = 0;
 
+	/*
+	 * If this is an error message, pre-emptively clear any incomplete query
+	 * result we may have.  We'd just throw it away below anyway, and
+	 * releasing it before collecting the error might avoid out-of-memory.
+	 */
+	if (isError)
+		pqClearAsyncResult(conn);
+
 	/*
 	 * Since the fields might be pretty long, we create a temporary
 	 * PQExpBuffer rather than using conn->workBuffer.  workBuffer is intended
@@ -1030,7 +1038,7 @@ pqGetErrorNotice3(PGconn *conn, bool isError)
 	{
 		if (res)
 			res->errMsg = pqResultStrdup(res, workBuf.data);
-		pqClearAsyncResult(conn);
+		pqClearAsyncResult(conn);	/* redundant, but be safe */
 		conn->result = res;
 		if (PQExpBufferDataBroken(workBuf))
 			printfPQExpBuffer(&conn->errorMessage,