diff --git a/daemon/logging/trace/trace.go b/daemon/logging/trace/trace.go
index 8421800..08caea2 100644
--- a/daemon/logging/trace/trace.go
+++ b/daemon/logging/trace/trace.go
@@ -246,7 +246,7 @@ func WithTask(ctx context.Context, taskName string) (context.Context, DoneFunc)
 					// the debugString can be quite long and panic won't print it completely
 					fmt.Fprintf(os.Stderr, "going to panic due to activeChildTasks:\n%s\n", this.debugString())
 				}
-				panic(errors.WithMessagef(ErrTaskStillHasActiveChildTasks, "end task: %v active child tasks\n", this.activeChildTasks))
+				panic(errors.WithMessagef(ErrTaskStillHasActiveChildTasks, "end task: %v active child tasks (run daemon with env var %s=1 for more details)\n", this.activeChildTasks, debugEnabledEnvVar))
 			}
 
 			// support idempotent task ends
diff --git a/daemon/logging/trace/trace_debug.go b/daemon/logging/trace/trace_debug.go
index 93ca6e7..c12f80f 100644
--- a/daemon/logging/trace/trace_debug.go
+++ b/daemon/logging/trace/trace_debug.go
@@ -7,7 +7,9 @@ import (
 	"github.com/zrepl/zrepl/util/envconst"
 )
 
-var debugEnabled = envconst.Bool("ZREPL_TRACE_DEBUG_ENABLED", false)
+const debugEnabledEnvVar = "ZREPL_TRACE_DEBUG_ENABLED"
+
+var debugEnabled = envconst.Bool(debugEnabledEnvVar, false)
 
 func debug(format string, args ...interface{}) {
 	if !debugEnabled {