diff --git a/tests/camera2/CameraModuleFixture.h b/tests/camera2/CameraModuleFixture.h
index 3a2df69..102fa6d 100644
--- a/tests/camera2/CameraModuleFixture.h
+++ b/tests/camera2/CameraModuleFixture.h
@@ -36,7 +36,7 @@
 template <bool InfoQuirk = false>
 struct CameraModuleFixture {
 
-    CameraModuleFixture(int CameraID = -1) {
+    explicit CameraModuleFixture(int CameraID = -1) {
         TEST_EXTENSION_FORKING_CONSTRUCTOR;
 
         mCameraID = CameraID;
diff --git a/tests/camera2/CameraStreamFixture.h b/tests/camera2/CameraStreamFixture.h
index bf7fb42..92ff05b 100644
--- a/tests/camera2/CameraStreamFixture.h
+++ b/tests/camera2/CameraStreamFixture.h
@@ -71,7 +71,7 @@
     : public CameraModuleFixture</*InfoQuirk*/true> {
 
 public:
-    CameraStreamFixture(CameraStreamParams p)
+    explicit CameraStreamFixture(CameraStreamParams p)
     : CameraModuleFixture(TestSettings::DeviceId()) {
         TEST_EXTENSION_FORKING_CONSTRUCTOR;
 
diff --git a/tests/camera2/camera2_utils.h b/tests/camera2/camera2_utils.h
index ab1fcfb..a01bae2 100644
--- a/tests/camera2/camera2_utils.h
+++ b/tests/camera2/camera2_utils.h
@@ -166,7 +166,7 @@
  */
 class StreamAdapter: public camera2_stream_ops {
   public:
-    StreamAdapter(sp<IGraphicBufferProducer> consumer);
+    explicit StreamAdapter(sp<IGraphicBufferProducer> consumer);
 
     ~StreamAdapter();
 
diff --git a/tests/input/evdev/TestHelpers.h b/tests/input/evdev/TestHelpers.h
index 461db04..d26adfb 100644
--- a/tests/input/evdev/TestHelpers.h
+++ b/tests/input/evdev/TestHelpers.h
@@ -42,7 +42,7 @@
  */
 class TempFile {
 public:
-    TempFile(const char* path);
+    explicit TempFile(const char* path);
     ~TempFile();
 
     // No copy or assign