diff --git a/src/os/os_unix_test.go b/src/os/os_unix_test.go
index 7e7281955b..41feaf77e2 100644
--- a/src/os/os_unix_test.go
+++ b/src/os/os_unix_test.go
@@ -64,7 +64,7 @@ func TestChown(t *testing.T) {
 	// Then try all the auxiliary groups.
 	groups, err := Getgroups()
 	if err != nil {
-		t.Fatalf("getgroups: %s", err)
+		t.Fatal(err)
 	}
 	t.Log("groups: ", groups)
 	for _, g := range groups {
@@ -112,7 +112,7 @@ func TestFileChown(t *testing.T) {
 	// Then try all the auxiliary groups.
 	groups, err := Getgroups()
 	if err != nil {
-		t.Fatalf("getgroups: %s", err)
+		t.Fatal(err)
 	}
 	t.Log("groups: ", groups)
 	for _, g := range groups {
@@ -170,7 +170,7 @@ func TestLchown(t *testing.T) {
 	// Then try all the auxiliary groups.
 	groups, err := Getgroups()
 	if err != nil {
-		t.Fatalf("getgroups: %s", err)
+		t.Fatal(err)
 	}
 	t.Log("groups: ", groups)
 	for _, g := range groups {
diff --git a/src/os/root_unix_test.go b/src/os/root_unix_test.go
index 0562af1f5e..b4b37c2be9 100644
--- a/src/os/root_unix_test.go
+++ b/src/os/root_unix_test.go
@@ -30,7 +30,7 @@ func TestRootChown(t *testing.T) {
 
 	groups, err := os.Getgroups()
 	if err != nil {
-		t.Fatalf("getgroups: %v", err)
+		t.Fatal(err)
 	}
 	groups = append(groups, os.Getgid())
 	for _, test := range rootTestCases {
@@ -66,7 +66,7 @@ func TestRootLchown(t *testing.T) {
 
 	groups, err := os.Getgroups()
 	if err != nil {
-		t.Fatalf("getgroups: %v", err)
+		t.Fatal(err)
 	}
 	groups = append(groups, os.Getgid())
 	for _, test := range rootTestCases {
@@ -97,7 +97,7 @@ func TestRootConsistencyChown(t *testing.T) {
 	}
 	groups, err := os.Getgroups()
 	if err != nil {
-		t.Fatalf("getgroups: %v", err)
+		t.Fatal(err)
 	}
 	var gid int
 	if len(groups) == 0 {
@@ -133,7 +133,7 @@ func TestRootConsistencyLchown(t *testing.T) {
 	}
 	groups, err := os.Getgroups()
 	if err != nil {
-		t.Fatalf("getgroups: %v", err)
+		t.Fatal(err)
 	}
 	var gid int
 	if len(groups) == 0 {