diff --git a/cmd/hammyd/keygen.go b/cmd/hammyd/keygen.go
index 4449317..bfb7d3b 100644
--- a/cmd/hammyd/keygen.go
+++ b/cmd/hammyd/keygen.go
@@ -63,9 +63,14 @@ func runKeygen(ctx context.Context, args []string) error {
 
 	owner, err := q.OwnerByEmail(ctx, normEmail)
 	if errors.Is(err, pgx.ErrNoRows) {
+		var callsignArg any
+		if normCall != "" {
+			callsignArg = normCall
+		}
+
 		created, cerr := q.CreateOwner(ctx, db.CreateOwnerParams{
 			Email:    normEmail,
-			Callsign: nullableCallsign(normCall),
+			Callsign: callsignArg,
 		})
 		if cerr != nil {
 			return fmt.Errorf("keygen: creating owner: %w", cerr)
@@ -97,7 +102,7 @@ func runKeygen(ctx context.Context, args []string) error {
 		Label:     nullableString(*label),
 		Scopes:    scopeList,
 		QuotaTier: *tier,
-		ExpiresAt: expiresAt,
+		ExpiresAt: db.Timestamptz(expiresAt),
 	})
 	if err != nil {
 		// The keys_scopes_known CHECK rejects unknown scopes, which is the
@@ -149,11 +154,3 @@ func nullableString(s string) *string {
 
 	return &s
 }
-
-func nullableCallsign(s string) *string {
-	if s == "" {
-		return nil
-	}
-
-	return &s
-}