diff --git a/app/vmalert/README.md b/app/vmalert/README.md
index a34ad0902..0fd6e4dde 100644
--- a/app/vmalert/README.md
+++ b/app/vmalert/README.md
@@ -211,7 +211,7 @@ The shortlist of configuration flags is the following:
   -datasource.maxIdleConnections int
     	Defines the number of idle (keep-alive connections) to each configured datasource. Consider setting this value equal to the value: groups_total * group.concurrency. Too low a value may result in a high number of sockets in TIME_WAIT state. (default 100)
   -datasource.queryStep duration
-    	queryStep defines how far a value can fallback to when evaluating queries. For example, if datasource.queryStep=15s then param "step" with value "15s" will be added to every query.
+    	queryStep defines how far a value can fallback to when evaluating queries. For example, if datasource.queryStep=15s then param "step" with value "15s" will be added to every query.If queryStep isn't specified, rule's evaluationInterval will be used instead.
   -datasource.tlsCAFile string
     	Optional path to TLS CA file to use for verifying connections to -datasource.url. By default, system CA is used
   -datasource.tlsCertFile string
diff --git a/docs/vmalert.md b/docs/vmalert.md
index 45dce761d..18cc96804 100644
--- a/docs/vmalert.md
+++ b/docs/vmalert.md
@@ -215,7 +215,7 @@ The shortlist of configuration flags is the following:
   -datasource.maxIdleConnections int
     	Defines the number of idle (keep-alive connections) to each configured datasource. Consider setting this value equal to the value: groups_total * group.concurrency. Too low a value may result in a high number of sockets in TIME_WAIT state. (default 100)
   -datasource.queryStep duration
-    	queryStep defines how far a value can fallback to when evaluating queries. For example, if datasource.queryStep=15s then param "step" with value "15s" will be added to every query.
+    	queryStep defines how far a value can fallback to when evaluating queries. For example, if datasource.queryStep=15s then param "step" with value "15s" will be added to every query.If queryStep isn't specified, rule's evaluationInterval will be used instead.
   -datasource.tlsCAFile string
     	Optional path to TLS CA file to use for verifying connections to -datasource.url. By default, system CA is used
   -datasource.tlsCertFile string