diff --git a/src/cmd/compile/fmt_test.go b/src/cmd/compile/fmt_test.go
index eaa2aa8dbd..05d13b58a5 100644
--- a/src/cmd/compile/fmt_test.go
+++ b/src/cmd/compile/fmt_test.go
@@ -660,6 +660,7 @@ var knownFormats = map[string]string{
 	"cmd/compile/internal/ssa.rbrank %d":              "",
 	"cmd/compile/internal/ssa.regMask %d":             "",
 	"cmd/compile/internal/ssa.register %d":            "",
+	"cmd/compile/internal/syntax.Error %q":            "",
 	"cmd/compile/internal/syntax.Expr %#v":            "",
 	"cmd/compile/internal/syntax.Node %T":             "",
 	"cmd/compile/internal/syntax.Operator %s":         "",