diff --git a/cmd/gomobile/build_androidapp.go b/cmd/gomobile/build_androidapp.go
index 6bbdf8e..a1f07cb 100644
--- a/cmd/gomobile/build_androidapp.go
+++ b/cmd/gomobile/build_androidapp.go
@@ -152,7 +152,7 @@
 	}
 	dexData, err := base64.StdEncoding.DecodeString(dexStr)
 	if err != nil {
-		log.Fatal("internal error bad dexStr: %v", err)
+		log.Fatalf("internal error bad dexStr: %v", err)
 	}
 	if _, err := w.Write(dexData); err != nil {
 		return nil, err
diff --git a/cmd/gomobile/cert_test.go b/cmd/gomobile/cert_test.go
index de1275f..359d7ad 100644
--- a/cmd/gomobile/cert_test.go
+++ b/cmd/gomobile/cert_test.go
@@ -62,7 +62,7 @@
 	if keytool, err := exec.LookPath("keytool"); err != nil {
 		t.Log("command keytool not found, skipping")
 	} else if err := exec.Command(keytool, "-v").Run(); err != nil {
-		t.Log("command keytool not functioning: %s, skipping", err)
+		t.Logf("command keytool not functioning: %s, skipping", err)
 	} else {
 		cmd := exec.Command(keytool, "-v", "-printcert", "-file", sigPath)
 		out, err := cmd.CombinedOutput()
diff --git a/internal/importers/java/java.go b/internal/importers/java/java.go
index b294e6d..4f1c89e 100644
--- a/internal/importers/java/java.go
+++ b/internal/importers/java/java.go
@@ -611,7 +611,7 @@
 	out, err := javap.CombinedOutput()
 	if err != nil {
 		if _, ok := err.(*exec.ExitError); !ok {
-			return nil, fmt.Errorf("javap failed: %v: %s", err)
+			return nil, fmt.Errorf("javap failed: %v", err)
 		}
 		// Not every name is a Java class so an exit error from javap is not
 		// fatal.