diff --git a/src/pkg/crypto/cipher/ocfb_test.go b/src/pkg/crypto/cipher/ocfb_test.go
index 7aae27bec91..40938b58923 100644
--- a/src/pkg/crypto/cipher/ocfb_test.go
+++ b/src/pkg/crypto/cipher/ocfb_test.go
@@ -27,7 +27,7 @@ func testOCFB(t *testing.T, resync OCFBResyncOption) {
 
 	ocfbdec := NewOCFBDecrypter(block, prefix, resync)
 	if ocfbdec == nil {
-		t.Error("NewOCFBDecrypter failed (resync: %t)", resync)
+		t.Errorf("NewOCFBDecrypter failed (resync: %t)", resync)
 		return
 	}
 	plaintextCopy := make([]byte, len(plaintext))
diff --git a/src/pkg/crypto/openpgp/packet/packet_test.go b/src/pkg/crypto/openpgp/packet/packet_test.go
index 050b7341fb8..6789d2abc79 100644
--- a/src/pkg/crypto/openpgp/packet/packet_test.go
+++ b/src/pkg/crypto/openpgp/packet/packet_test.go
@@ -115,7 +115,7 @@ func TestPartialLengthReader(t *testing.T) {
 
 		got := fmt.Sprintf("%x", out)
 		if got != test.hexOutput {
-			t.Errorf("%d: got:%s want:%s", test.hexOutput, got)
+			t.Errorf("%d: got:%s want:%s", i, test.hexOutput, got)
 		}
 	}
 }
diff --git a/src/pkg/exp/eval/stmt.go b/src/pkg/exp/eval/stmt.go
index 77ff066d09c..5c5d4338a1d 100644
--- a/src/pkg/exp/eval/stmt.go
+++ b/src/pkg/exp/eval/stmt.go
@@ -908,7 +908,7 @@ func (a *stmtCompiler) compileBranchStmt(s *ast.BranchStmt) {
 		return
 
 	default:
-		log.Panic("Unexpected branch token %v", s.Tok)
+		log.Panicf("Unexpected branch token %v", s.Tok)
 	}
 
 	a.flow.put1(false, pc)
diff --git a/src/pkg/template/template_test.go b/src/pkg/template/template_test.go
index 9df3ab59c00..d21a5397a15 100644
--- a/src/pkg/template/template_test.go
+++ b/src/pkg/template/template_test.go
@@ -740,7 +740,7 @@ func TestFormatters(t *testing.T) {
 				continue
 			}
 			if strings.Index(err.String(), c.err) < 0 {
-				t.Error("unexpected error: expected %q, got %q", c.err, err.String())
+				t.Errorf("unexpected error: expected %q, got %q", c.err, err.String())
 				continue
 			}
 		} else {