diff --git a/src/fmt/format.go b/src/fmt/format.go
index 617f78f15ea2b..b497ad0f1b474 100644
--- a/src/fmt/format.go
+++ b/src/fmt/format.go
@@ -53,6 +53,8 @@ type fmt struct {
 
 func (f *fmt) clearflags() {
 	f.fmtFlags = fmtFlags{}
+	f.wid = 0
+	f.prec = 0
 }
 
 func (f *fmt) init(buf *buffer) {