diff --git a/.github/workflows/run-tests.yml b/.github/workflows/run-tests.yml
index d97ad12a6..c1b626782 100644
--- a/.github/workflows/run-tests.yml
+++ b/.github/workflows/run-tests.yml
@@ -23,6 +23,7 @@ jobs:
           - 15
           - 16
           - 17
+          - 18
         TEST:
           - multi
           - single
diff --git a/src/bin/lib/pg/snprintf.c b/src/bin/lib/pg/snprintf.c
index 5831818f3..94dbfa6b9 100644
--- a/src/bin/lib/pg/snprintf.c
+++ b/src/bin/lib/pg/snprintf.c
@@ -550,16 +550,12 @@ dopr(PrintfTarget *target, const char *format, va_list args)
 					longflag = 1;
 				goto nextch2;
 			case 'z':
-#if SIZEOF_SIZE_T == 8
-#ifdef HAVE_LONG_INT_64
+#if SIZEOF_SIZE_T == SIZEOF_LONG
 				longflag = 1;
-#elif defined(HAVE_LONG_LONG_INT_64)
+#elif SIZEOF_SIZE_T == SIZEOF_LONG_LONG
 				longlongflag = 1;
 #else
-#error "Don't know how to print 64bit integers"
-#endif
-#else
-				/* assume size_t is same size as int */
+#error "cannot find integer type of the same size as size_t"
 #endif
 				goto nextch2;
 			case 'h':
@@ -817,16 +813,12 @@ find_arguments(const char *format, va_list args,
 					longflag = 1;
 				goto nextch1;
 			case 'z':
-#if SIZEOF_SIZE_T == 8
-#ifdef HAVE_LONG_INT_64
+#if SIZEOF_SIZE_T == SIZEOF_LONG
 				longflag = 1;
-#elif defined(HAVE_LONG_LONG_INT_64)
+#elif SIZEOF_SIZE_T == SIZEOF_LONG_LONG
 				longlongflag = 1;
 #else
-#error "Don't know how to print 64bit integers"
-#endif
-#else
-				/* assume size_t is same size as int */
+#error "cannot find integer type of the same size as size_t"
 #endif
 				goto nextch1;
 			case 'h':
diff --git a/src/monitor/expected/upgrade_1.out b/src/monitor/expected/upgrade_1.out
new file mode 100644
index 000000000..bc323db63
--- /dev/null
+++ b/src/monitor/expected/upgrade_1.out
@@ -0,0 +1,35 @@
+-- Copyright (c) Microsoft Corporation. All rights reserved.
+-- Licensed under the PostgreSQL License.
+CREATE EXTENSION pgautofailover VERSION '1.0';
+\dx pgautofailover
+                      List of installed extensions
+      Name      | Version | Default version | Schema |   Description    
+----------------+---------+-----------------+--------+------------------
+ pgautofailover | 1.0     | 2.2             | public | pg_auto_failover
+(1 row)
+
+ALTER EXTENSION pgautofailover UPDATE TO '1.1';
+\dx pgautofailover
+                      List of installed extensions
+      Name      | Version | Default version | Schema |   Description    
+----------------+---------+-----------------+--------+------------------
+ pgautofailover | 1.1     | 2.2             | public | pg_auto_failover
+(1 row)
+
+ALTER EXTENSION pgautofailover UPDATE TO '1.2';
+\dx pgautofailover
+                      List of installed extensions
+      Name      | Version | Default version | Schema |   Description    
+----------------+---------+-----------------+--------+------------------
+ pgautofailover | 1.2     | 2.2             | public | pg_auto_failover
+(1 row)
+
+ALTER EXTENSION pgautofailover UPDATE TO '1.3';
+\dx pgautofailover
+                      List of installed extensions
+      Name      | Version | Default version | Schema |   Description    
+----------------+---------+-----------------+--------+------------------
+ pgautofailover | 1.3     | 2.2             | public | pg_auto_failover
+(1 row)
+
+DROP EXTENSION pgautofailover;
diff --git a/src/monitor/node_metadata.c b/src/monitor/node_metadata.c
index 07748c616..f80d2572b 100644
--- a/src/monitor/node_metadata.c
+++ b/src/monitor/node_metadata.c
@@ -19,6 +19,7 @@
 /* list_qsort is only in Postgres 11 and 12 */
 #include "version_compat.h"
 
+#include "group_state_machine.h"
 #include "health_check.h"
 #include "metadata.h"
 #include "node_metadata.h"
diff --git a/src/monitor/pg_auto_failover.c b/src/monitor/pg_auto_failover.c
index c780a8fd4..e7c468627 100644
--- a/src/monitor/pg_auto_failover.c
+++ b/src/monitor/pg_auto_failover.c
@@ -35,7 +35,7 @@
 #include "tcop/utility.h"
 
 
-ProcessUtility_hook_type PreviousProcessUtility_hook = NULL;
+static ProcessUtility_hook_type PreviousProcessUtility_hook = NULL;
 
 
 #if PG_VERSION_NUM >= 150000
diff --git a/src/monitor/version_compat.h b/src/monitor/version_compat.h
index 088f53909..82f36abc0 100644
--- a/src/monitor/version_compat.h
+++ b/src/monitor/version_compat.h
@@ -14,8 +14,8 @@
 
 #include "postgres.h"
 
-/* we support Postgres versions 10, 11, 12, 13, 14, 15, 16, and 17. */
-#if (PG_VERSION_NUM < 100000 || PG_VERSION_NUM >= 180000)
+/* we support Postgres versions 10, 11, 12, 13, 14, 15, 16, 17, 18. */
+#if (PG_VERSION_NUM < 100000 || PG_VERSION_NUM >= 190000)
 #error "Unknown or unsupported postgresql version"
 #endif