diff --git a/wrapcheck/testdata/interface_on_struct/main.go b/wrapcheck/testdata/interface_on_struct/main.go
index f845015..c2cf892 100644
--- a/wrapcheck/testdata/interface_on_struct/main.go
+++ b/wrapcheck/testdata/interface_on_struct/main.go
@@ -1,12 +1,8 @@
 package main
 
-import (
-	"encoding/json"
-	"strings"
-)
-
 type errorer interface {
 	Decode(v interface{}) error
+	decode(v interface{}) error
 }
 
 type foo struct {
@@ -14,8 +10,8 @@ type foo struct {
 }
 
 func main() {
-	d := json.NewDecoder(strings.NewReader("hello world"))
-	do(foo{d})
+	do(foo{})
+	doInternal(foo{})
 }
 
 func do(f foo) error {
@@ -27,3 +23,13 @@ func do(f foo) error {
 
 	return nil
 }
+
+func doInternal(f foo) error {
+	var str string
+	err := f.bar.decode(&str)
+	if err != nil {
+		return err // unexported methods are validated at their implementation
+	}
+
+	return nil
+}
diff --git a/wrapcheck/wrapcheck.go b/wrapcheck/wrapcheck.go
index 79e7bba..2c1b2d2 100644
--- a/wrapcheck/wrapcheck.go
+++ b/wrapcheck/wrapcheck.go
@@ -283,9 +283,9 @@ func reportUnwrapped(
 	}
 
 	// Check if the underlying type of the "x" in x.y.z is an interface, as
-	// errors returned from interface types should be wrapped, unless ignored
-	// as per `ignoreInterfaceRegexps`
-	if isInterface(pass, sel) {
+	// errors returned from exported interface types should be wrapped, unless
+	// ignored as per `ignoreInterfaceRegexps`
+	if sel.Sel.IsExported() && isInterface(pass, sel) {
 		pkgPath := pass.TypesInfo.ObjectOf(sel.Sel).Pkg().Path()
 		name := types.TypeString(pass.TypesInfo.TypeOf(sel.X), func(p *types.Package) string { return p.Name() })
 		if !containsMatch(regexpsInter, name) && !containsMatchGlob(pkgGlobs, pkgPath) {