diff --git a/src/backend/backup/basebackup.c b/src/backend/backup/basebackup.c
index 5fbbe5ffd2..5fea86ad0f 100644
--- a/src/backend/backup/basebackup.c
+++ b/src/backend/backup/basebackup.c
@@ -397,8 +397,7 @@ perform_base_backup(basebackup_options *opt, bbsink *sink,
 		endtli = backup_state->stoptli;
 
 		/* Deallocate backup-related variables. */
-		pfree(tablespace_map->data);
-		pfree(tablespace_map);
+		destroyStringInfo(tablespace_map);
 		pfree(backup_state);
 	}
 	PG_END_ENSURE_ERROR_CLEANUP(do_pg_abort_backup, BoolGetDatum(false));
diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index a05d69922d..5a47fa984d 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -506,8 +506,7 @@ check_publications(WalReceiverConn *wrconn, List *publications)
 	appendStringInfoChar(cmd, ')');
 
 	res = walrcv_exec(wrconn, cmd->data, 1, tableRow);
-	pfree(cmd->data);
-	pfree(cmd);
+	destroyStringInfo(cmd);
 
 	if (res->status != WALRCV_OK_TUPLES)
 		ereport(ERROR,
diff --git a/src/backend/utils/adt/jsonb.c b/src/backend/utils/adt/jsonb.c
index a5e48744ac..a941654d5a 100644
--- a/src/backend/utils/adt/jsonb.c
+++ b/src/backend/utils/adt/jsonb.c
@@ -133,8 +133,7 @@ jsonb_send(PG_FUNCTION_ARGS)
 	pq_begintypsend(&buf);
 	pq_sendint8(&buf, version);
 	pq_sendtext(&buf, jtext->data, jtext->len);
-	pfree(jtext->data);
-	pfree(jtext);
+	destroyStringInfo(jtext);
 
 	PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
 }
diff --git a/src/backend/utils/adt/xml.c b/src/backend/utils/adt/xml.c
index beecd0c2ac..3e4ca874d8 100644
--- a/src/backend/utils/adt/xml.c
+++ b/src/backend/utils/adt/xml.c
@@ -2163,8 +2163,7 @@ xml_errorHandler(void *data, PgXmlErrorPtr error)
 		appendBinaryStringInfo(&xmlerrcxt->err_buf, errorBuf->data,
 							   errorBuf->len);
 
-		pfree(errorBuf->data);
-		pfree(errorBuf);
+		destroyStringInfo(errorBuf);
 		return;
 	}
 
@@ -2195,8 +2194,7 @@ xml_errorHandler(void *data, PgXmlErrorPtr error)
 				(errmsg_internal("%s", errorBuf->data)));
 	}
 
-	pfree(errorBuf->data);
-	pfree(errorBuf);
+	destroyStringInfo(errorBuf);
 }
 
 
diff --git a/src/bin/pg_combinebackup/pg_combinebackup.c b/src/bin/pg_combinebackup/pg_combinebackup.c
index 6f0814d9ac..74f8be9eea 100644
--- a/src/bin/pg_combinebackup/pg_combinebackup.c
+++ b/src/bin/pg_combinebackup/pg_combinebackup.c
@@ -526,10 +526,7 @@ check_backup_label_files(int n_backups, char **backup_dirs)
 
 	/* Free memory that we don't need any more. */
 	if (lastbuf != buf)
-	{
-		pfree(buf->data);
-		pfree(buf);
-	}
+		destroyStringInfo(buf);
 
 	/*
 	 * Return the data from the first backup_info that we read (which is the
diff --git a/src/common/stringinfo.c b/src/common/stringinfo.c
index c61d5c58f3..ec5fc2422d 100644
--- a/src/common/stringinfo.c
+++ b/src/common/stringinfo.c
@@ -350,3 +350,19 @@ enlargeStringInfo(StringInfo str, int needed)
 
 	str->maxlen = newlen;
 }
+
+/*
+ * destroyStringInfo
+ *
+ * Frees a StringInfo and its buffer (opposite of makeStringInfo()).
+ * This must only be called on palloc'd StringInfos.
+ */
+void
+destroyStringInfo(StringInfo str)
+{
+	/* don't allow destroys of read-only StringInfos */
+	Assert(str->maxlen != 0);
+
+	pfree(str->data);
+	pfree(str);
+}
diff --git a/src/include/lib/stringinfo.h b/src/include/lib/stringinfo.h
index 2cd636b01c..cd9632e3fc 100644
--- a/src/include/lib/stringinfo.h
+++ b/src/include/lib/stringinfo.h
@@ -87,7 +87,8 @@ typedef StringInfoData *StringInfo;
  *		to be len + 1 in size.
  *
  * To destroy a StringInfo, pfree() the data buffer, and then pfree() the
- * StringInfoData if it was palloc'd.  There's no special support for this.
+ * StringInfoData if it was palloc'd.  For StringInfos created with
+ * makeStringInfo(), destroyStringInfo() is provided for this purpose.
  * However, if the StringInfo was initialized using initReadOnlyStringInfo()
  * then the caller will need to consider if it is safe to pfree the data
  * buffer.
@@ -233,4 +234,10 @@ extern void appendBinaryStringInfoNT(StringInfo str,
  */
 extern void enlargeStringInfo(StringInfo str, int needed);
 
+/*------------------------
+ * destroyStringInfo
+ * Frees a StringInfo and its buffer (opposite of makeStringInfo()).
+ */
+extern void destroyStringInfo(StringInfo str);
+
 #endif							/* STRINGINFO_H */
diff --git a/src/test/regress/pg_regress.c b/src/test/regress/pg_regress.c
index f1f6011ae0..76f01c73f5 100644
--- a/src/test/regress/pg_regress.c
+++ b/src/test/regress/pg_regress.c
@@ -1174,8 +1174,7 @@ psql_end_command(StringInfo buf, const char *database)
 	}
 
 	/* Clean up */
-	pfree(buf->data);
-	pfree(buf);
+	destroyStringInfo(buf);
 }
 
 /*