diff --git a/migrations/20211215_migrate_id_to_bigint.go b/migrations/20211215_migrate_id_to_bigint.go
index 6298641..99cd043 100644
--- a/migrations/20211215_migrate_id_to_bigint.go
+++ b/migrations/20211215_migrate_id_to_bigint.go
@@ -15,6 +15,8 @@ func init() {
 				return nil
 			}
 
+			logbuch.Info("this may take a while!")
+
 			if cfg.Db.IsMySQL() {
 				tx := db.Begin()
 				if err := tx.Exec("ALTER TABLE heartbeats MODIFY COLUMN id BIGINT UNSIGNED AUTO_INCREMENT").Error; err != nil {
diff --git a/migrations/20212212_total_summary_heartbeats.go b/migrations/20212212_total_summary_heartbeats.go
new file mode 100644
index 0000000..b929d6e
--- /dev/null
+++ b/migrations/20212212_total_summary_heartbeats.go
@@ -0,0 +1,48 @@
+package migrations
+
+import (
+	"database/sql"
+	"github.com/emvi/logbuch"
+	"github.com/muety/wakapi/config"
+	"github.com/muety/wakapi/models"
+	"gorm.io/gorm"
+)
+
+func init() {
+	const name = "20212212-total_summary_heartbeats"
+	f := migrationFunc{
+		name: name,
+		f: func(db *gorm.DB, cfg *config.Config) error {
+			if hasRun(name, db) {
+				return nil
+			}
+
+			logbuch.Info("this may take a while!")
+
+			// this turns out to actually be way faster than using joins and instead has the benefit of being cross-dialect compatible
+
+			var summaries []*models.Summary
+			if err := db.Model(&models.Summary{}).
+				Select("id, from_time, to_time, user_id").
+				Scan(&summaries).Error; err != nil {
+				return err
+			}
+
+			tx := db.Begin()
+			for _, s := range summaries {
+				query := "UPDATE summaries SET num_heartbeats = (SELECT count(id) AS num_heartbeats FROM heartbeats WHERE user_id = @user AND time BETWEEN @from AND @to) WHERE id = @id"
+				tx.Exec(query, sql.Named("from", s.FromTime), sql.Named("to", s.ToTime), sql.Named("id", s.ID), sql.Named("user", s.UserID))
+			}
+			if err := tx.Commit().Error; err != nil {
+				tx.Rollback()
+				logbuch.Error("failed to retroactively determine total summary heartbeats")
+				return err
+			}
+
+			setHasRun(name, db)
+			return nil
+		},
+	}
+
+	registerPostMigration(f)
+}
diff --git a/models/summary.go b/models/summary.go
index f7d4bb0..f52a12e 100644
--- a/models/summary.go
+++ b/models/summary.go
@@ -31,7 +31,7 @@ type Summary struct {
 	OperatingSystems SummaryItems `json:"operating_systems" gorm:"constraint:OnUpdate:CASCADE,OnDelete:CASCADE"`
 	Machines         SummaryItems `json:"machines" gorm:"constraint:OnUpdate:CASCADE,OnDelete:CASCADE"`
 	Labels           SummaryItems `json:"labels" gorm:"-"` // labels are not persisted, but calculated at runtime, i.e. when summary is retrieved
-	NumHeartbeats    int          `json:"-"`
+	NumHeartbeats    int          `json:"-" gorm:"default:0"`
 }
 
 type SummaryItems []*SummaryItem
diff --git a/views/signup.tpl.html b/views/signup.tpl.html
index 7387a52..2a527ae 100644
--- a/views/signup.tpl.html
+++ b/views/signup.tpl.html
@@ -81,9 +81,9 @@
 
             <div class="flex space-x-2 justify-end">
                 <a href="login">
-                    <button type="button" class="btn-primary">Log in</button>
+                    <button type="button" class="btn-default">Log in</button>
                 </a>
-                <button type="submit" class="btn-default">
+                <button type="submit" class="btn-primary">
                     Create Account
                 </button>
             </div>