diff --git a/doc/hooks.md b/doc/hooks.md
index 43ddb7e..1b1958f 100644
--- a/doc/hooks.md
+++ b/doc/hooks.md
@@ -69,6 +69,7 @@ The following variables are available on all hooks:
 - `GH_OST_INSPECTED_HOST`
 - `GH_OST_EXECUTING_HOST`
 - `GH_OST_HOOKS_HINT` - copy of `--hooks-hint` value
+- `GH_OST_DRY_RUN` - whether or not the `gh-ost` run is a dry run
 
 The following variable are available on particular hooks:
 
diff --git a/go/logic/hooks.go b/go/logic/hooks.go
index 1fdfd5c..6515d7f 100644
--- a/go/logic/hooks.go
+++ b/go/logic/hooks.go
@@ -64,6 +64,7 @@ func (this *HooksExecutor) applyEnvironmentVariables(extraVariables ...string) [
 	env = append(env, fmt.Sprintf("GH_OST_INSPECTED_HOST=%s", this.migrationContext.GetInspectorHostname()))
 	env = append(env, fmt.Sprintf("GH_OST_EXECUTING_HOST=%s", this.migrationContext.Hostname))
 	env = append(env, fmt.Sprintf("GH_OST_HOOKS_HINT=%s", this.migrationContext.HooksHintMessage))
+	env = append(env, fmt.Sprintf("GH_OST_DRY_RUN=%t", this.migrationContext.Noop))
 
 	for _, variable := range extraVariables {
 		env = append(env, variable)