diff --git a/_data/rules.yml b/_data/rules.yml
index 7589730..de00e7e 100644
--- a/_data/rules.yml
+++ b/_data/rules.yml
@@ -695,12 +695,14 @@ groups:
                 description: Redis has not been backuped for 24 hours
                 query: 'time() - redis_rdb_last_save_timestamp_seconds > 60 * 60 * 24'
                 severity: critical
-              - name: Redis out of memory (total system memory version)
+              - name: Redis out of system memory
                 description: Redis is running out of system memory (> 90%)
                 query: 'redis_memory_used_bytes / redis_total_system_memory_bytes * 100 > 90'
                 severity: warning
                 for: 2m
-              - name: Redis out of memory (maxmemory version)
+                comments: |
+                  The exporter must be started with --include-system-metrics flag or REDIS_EXPORTER_INCL_SYSTEM_METRICS=true environment variable.
+              - name: Redis out of configured maxmemory
                 description: Redis is running out of configured maxmemory (> 90%)
                 query: 'redis_memory_used_bytes / redis_memory_max_bytes * 100 > 90'
                 severity: warning