diff --git a/clause/on_conflict.go b/clause/on_conflict.go
index 2b17adf4..a589bd65 100644
--- a/clause/on_conflict.go
+++ b/clause/on_conflict.go
@@ -33,14 +33,14 @@ func (onConflict OnConflict) Build(builder Builder) {
 	}
 
 	if onConflict.DoNothing {
-		builder.WriteString("DO NOTHING ")
+		builder.WriteString("DO NOTHING")
 	} else {
 		builder.WriteString("DO UPDATE SET ")
 		onConflict.DoUpdates.Build(builder)
-		builder.WriteByte(' ')
 	}
 
 	if len(onConflict.Where.Exprs) > 0 {
+		builder.WriteByte(' ')
 		builder.WriteString("WHERE ")
 		onConflict.Where.Build(builder)
 		builder.WriteByte(' ')