diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index eb9e022..0bf9372 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -882,24 +882,7 @@ PostmasterMain(int argc, char *argv[])
 
 	/* And switch working directory into it */
 	ChangeToDataDir();
-
-	/*
-	 * Check for invalid combinations of GUC settings.
-	 */
-	if (ReservedBackends >= MaxConnections)
-	{
-		write_stderr("%s: superuser_reserved_connections (%d) must be less than max_connections (%d)\n",
-					 progname,
-					 ReservedBackends, MaxConnections);
-		ExitPostmaster(1);
-	}
-	if (XLogArchiveMode > ARCHIVE_MODE_OFF && wal_level == WAL_LEVEL_MINIMAL)
-		ereport(ERROR,
-				(errmsg("WAL archival cannot be enabled when wal_level is \"minimal\"")));
-	if (max_wal_senders > 0 && wal_level == WAL_LEVEL_MINIMAL)
-		ereport(ERROR,
-				(errmsg("WAL streaming (max_wal_senders > 0) requires wal_level \"replica\" or \"logical\"")));

 	/*
 	 * Other one-time internal sanity checks can go here, if they are fast.
 	 * (Put any slow processing further down, after postmaster.pid creation.)
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 2178e1c..77e47e9 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -7828,6 +7828,108 @@ write_auto_conf_file(int fd, const char *filename, ConfigVariable *head)
 	pfree(buf.data);
 }
 
+/*
+ * This function traverses a list of parameters
+ * to check for invalid config combinations
+ */
+void
+check_for_invalid_config_combinations(ConfigVariable **conf) {
+	ConfigVariable *item, *next;
+
+	for (item = *conf; item != NULL; item = next)
+	{
+		next = item->next;
+		ConfigVariable *pitem, *pnext;
+		
+		/*
+		 * We could avoid the O(N^2) behavior here with some additional 
+		 * state, but it seems unlikely to be worth the trouble.
+		 */
+		for (pitem = *conf; pitem != NULL; pitem = pnext)
+		{	
+			pnext = pitem->next;
+			if (!pitem->ignore) {
+				if (guc_name_compare(item->name, "superuser_reserved_connections") == 0 &&
+						guc_name_compare(pitem->name, "max_connections") == 0) {
+					int reserved_backends;
+					int max_connections;
+					if (!parse_int(item->value, &max_connections, 0, NULL)) {
+						ereport(ERROR,
+								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+										errmsg("invalid value for parameter \"%s\": \"%s\"",
+											   item->name, item->value)));
+					}
+
+					if (!parse_int(pitem->value, &reserved_backends, 0, NULL)) {
+						ereport(ERROR,
+								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+										errmsg("invalid value for parameter \"%s\": \"%s\"",
+											   item->name, item->value)));
+					}
+					
+					if (reserved_backends >= max_connections)
+					{
+						ereport(ERROR,
+								(errmsg("%s: superuser_reserved_connections (%d) must be less than max_connections (%d)\n",
+										progname,
+										ReservedBackends, MaxConnections)));
+					}
+				}
+
+				if (guc_name_compare(item->name, "archive_mode") == 0 &&
+					guc_name_compare(pitem->name, "wal_level") == 0) {
+					int WalLevel;
+					int xlog_archive_mode;
+					if (!parse_int(item->value, &xlog_archive_mode, 0, NULL)) {
+						ereport(ERROR,
+								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+										errmsg("invalid value for parameter \"%s\": \"%s\"",
+											   item->name, item->value)));
+					}
+
+					if (!parse_int(pitem->value, &WalLevel, 0, NULL)) {
+						ereport(ERROR,
+								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+										errmsg("invalid value for parameter \"%s\": \"%s\"",
+											   item->name, item->value)));
+					}
+
+					if (xlog_archive_mode > ARCHIVE_MODE_OFF && WalLevel == WAL_LEVEL_MINIMAL)
+					{
+						ereport(ERROR,
+								(errmsg("WAL archival cannot be enabled when wal_level is \"minimal\"")));
+					}
+				}
+
+				if (guc_name_compare(item->name, "max_wal_senders") == 0 &&
+					guc_name_compare(pitem->name, "wal_level") == 0) {
+					int WalLevel;
+					int max_wal_senders;
+					if (!parse_int(item->value, &max_wal_senders, 0, NULL)) {
+						ereport(ERROR,
+								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+										errmsg("invalid value for parameter \"%s\": \"%s\"",
+											   item->name, item->value)));
+					}
+
+					if (!parse_int(pitem->value, &WalLevel, 0, NULL)) {
+						ereport(ERROR,
+								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+										errmsg("invalid value for parameter \"%s\": \"%s\"",
+											   item->name, item->value)));
+					}
+
+					if (max_wal_senders > 0 && WalLevel == WAL_LEVEL_MINIMAL)
+					{
+						ereport(ERROR,
+								(errmsg("WAL streaming (max_wal_senders > 0) requires wal_level \"replica\" or \"logical\"")));
+					}
+				}
+			}
+		}
+	}
+}
+
 /*
  * Update the given list of configuration parameters, adding, replacing
  * or deleting the entry for item "name" (delete if "value" == NULL).
@@ -7988,7 +8090,7 @@ AlterSystemSetConfigFile(AlterSystemStmt *altersysstmt)
 						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 						 errmsg("invalid value for parameter \"%s\": \"%s\"",
 								name, value)));

 			if (record->vartype == PGC_STRING && newval.stringval != NULL)
 				free(newval.stringval);
 			if (newextra)
@@ -8051,8 +8153,16 @@ AlterSystemSetConfigFile(AlterSystemStmt *altersysstmt)
 								AutoConfFileName)));
 
 			FreeFile(infile);
+
+			/*
+			 * Check to ensure change is valid in combination
+			 * with other configuration settings.
+			 */
+			ConfigVariable *conf = ProcessConfigFileInternal(PGC_SIGHUP, false, DEBUG3);
+			check_for_invalid_config_combinations(&conf);
 		}
 
 		/*
 		 * Now, replace any existing entry with the new value, or add it if
 		 * not present.
diff --git a/src/include/utils/guc.h b/src/include/utils/guc.h
index 6791e0c..ef10364 100644
--- a/src/include/utils/guc.h
+++ b/src/include/utils/guc.h
@@ -354,6 +354,7 @@ extern bool SelectConfigFiles(const char *userDoption, const char *progname);
 extern void ResetAllOptions(void);
 extern void AtStart_GUC(void);
 extern int	NewGUCNestLevel(void);
+extern void check_for_invalid_config_combinations(ConfigVariable **conf);
 extern void AtEOXact_GUC(bool isCommit, int nestLevel);
 extern void BeginReportingGUCOptions(void);
 extern void ParseLongOption(const char *string, char **name, char **value);