diff --git a/stack_test.go b/stack_test.go
index cd7827b..da53daf 100644
--- a/stack_test.go
+++ b/stack_test.go
@@ -160,10 +160,7 @@ func TestTrimGOPATH(t *testing.T) {
 		fn := runtime.FuncForPC(pc)
 		file, _ := fn.FileLine(pc)
 		got := trimGOPATH(fn.Name(), file)
-		want := tt.want
-		if want != got {
-			t.Errorf("%v: want %q, got %q", tt.Frame, want, got)
-		}
+		testFormatRegexp(t, got, "%s", tt.want)
 	}
 }
 
@@ -174,24 +171,24 @@ func TestStackTrace(t *testing.T) {
 	}{{
 		New("ooh"), []string{
 			"github.com/pkg/errors.TestStackTrace\n" +
-				"\t.+/github.com/pkg/errors/stack_test.go:175",
+				"\t.+/github.com/pkg/errors/stack_test.go:172",
 		},
 	}, {
 		Wrap(New("ooh"), "ahh"), []string{
 			"github.com/pkg/errors.TestStackTrace\n" +
-				"\t.+/github.com/pkg/errors/stack_test.go:180", // this is the stack of Wrap, not New
+				"\t.+/github.com/pkg/errors/stack_test.go:177", // this is the stack of Wrap, not New
 		},
 	}, {
 		Cause(Wrap(New("ooh"), "ahh")), []string{
 			"github.com/pkg/errors.TestStackTrace\n" +
-				"\t.+/github.com/pkg/errors/stack_test.go:185", // this is the stack of New
+				"\t.+/github.com/pkg/errors/stack_test.go:182", // this is the stack of New
 		},
 	}, {
 		func() error { return New("ooh") }(), []string{
 			`github.com/pkg/errors.(func·005|TestStackTrace.func1)` +
-				"\n\t.+/github.com/pkg/errors/stack_test.go:190", // this is the stack of New
+				"\n\t.+/github.com/pkg/errors/stack_test.go:187", // this is the stack of New
 			"github.com/pkg/errors.TestStackTrace\n" +
-				"\t.+/github.com/pkg/errors/stack_test.go:190", // this is the stack of New's caller
+				"\t.+/github.com/pkg/errors/stack_test.go:187", // this is the stack of New's caller
 		},
 	}, {
 		Cause(func() error {
@@ -200,11 +197,11 @@ func TestStackTrace(t *testing.T) {
 			}()
 		}()), []string{
 			`github.com/pkg/errors.(func·006|TestStackTrace.func2.1)` +
-				"\n\t.+/github.com/pkg/errors/stack_test.go:199", // this is the stack of Errorf
+				"\n\t.+/github.com/pkg/errors/stack_test.go:196", // this is the stack of Errorf
 			`github.com/pkg/errors.(func·007|TestStackTrace.func2)` +
-				"\n\t.+/github.com/pkg/errors/stack_test.go:200", // this is the stack of Errorf's caller
+				"\n\t.+/github.com/pkg/errors/stack_test.go:197", // this is the stack of Errorf's caller
 			"github.com/pkg/errors.TestStackTrace\n" +
-				"\t.+/github.com/pkg/errors/stack_test.go:201", // this is the stack of Errorf's caller's caller
+				"\t.+/github.com/pkg/errors/stack_test.go:198", // this is the stack of Errorf's caller's caller
 		},
 	}}
 	for _, tt := range tests {
@@ -274,19 +271,19 @@ func TestStackTraceFormat(t *testing.T) {
 	}, {
 		stackTrace()[:2],
 		"%v",
-		`\[stack_test.go:228 stack_test.go:275\]`,
+		`\[stack_test.go:225 stack_test.go:272\]`,
 	}, {
 		stackTrace()[:2],
 		"%+v",
 		"\n" +
 			"github.com/pkg/errors.stackTrace\n" +
-			"\t.+/github.com/pkg/errors/stack_test.go:228\n" +
+			"\t.+/github.com/pkg/errors/stack_test.go:225\n" +
 			"github.com/pkg/errors.TestStackTraceFormat\n" +
-			"\t.+/github.com/pkg/errors/stack_test.go:279",
+			"\t.+/github.com/pkg/errors/stack_test.go:276",
 	}, {
 		stackTrace()[:2],
 		"%#v",
-		`\[\]errors.Frame{stack_test.go:228, stack_test.go:287}`,
+		`\[\]errors.Frame{stack_test.go:225, stack_test.go:284}`,
 	}}
 
 	for _, tt := range tests {