diff --git a/sa/type-converter.go b/sa/type-converter.go
index b746449cdf1..15250c50cd0 100644
--- a/sa/type-converter.go
+++ b/sa/type-converter.go
@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"time"
 
 	"github.com/letsencrypt/borp"
 	"gopkg.in/go-jose/go-jose.v2"
@@ -34,6 +35,10 @@ func (tc BoulderTypeConverter) ToDb(val interface{}) (interface{}, error) {
 		return string(t), nil
 	case core.OCSPStatus:
 		return string(t), nil
+	case time.Time:
+		// All of our MySQL DATETIME columns have only Second-level precision, so
+		// don't bother sending more precision than the database will use.
+		return t.Truncate(time.Second), nil
 	default:
 		return val, nil
 	}