diff --git a/lang/c++/impl/FileStream.cc b/lang/c++/impl/FileStream.cc
index 7adcdfb8b19..17926af9d7d 100644
--- a/lang/c++/impl/FileStream.cc
+++ b/lang/c++/impl/FileStream.cc
@@ -49,7 +49,7 @@ struct BufferCopyIn {
 struct FileBufferCopyIn : public BufferCopyIn {
 #ifdef _WIN32
     HANDLE h_;
-    FileBufferCopyIn(const char *filename) : h_(::CreateFileA(filename, GENERIC_READ, 0, NULL, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL)) {
+    explicit FileBufferCopyIn(const char *filename) : h_(::CreateFileA(filename, GENERIC_READ, 0, NULL, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL)) {
         if (h_ == INVALID_HANDLE_VALUE) {
             throw Exception(boost::format("Cannot open file: %1%") % ::GetLastError());
         }
@@ -232,7 +232,7 @@ struct BufferCopyOut {
 struct FileBufferCopyOut : public BufferCopyOut {
 #ifdef _WIN32
     HANDLE h_;
-    FileBufferCopyOut(const char *filename) : h_(::CreateFileA(filename, GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL)) {
+    explicit FileBufferCopyOut(const char *filename) : h_(::CreateFileA(filename, GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL)) {
         if (h_ == INVALID_HANDLE_VALUE) {
             throw Exception(boost::format("Cannot open file: %1%") % ::GetLastError());
         }
diff --git a/lang/c++/impl/json/JsonDom.hh b/lang/c++/impl/json/JsonDom.hh
index 3fb5670b70b..2a0695adff6 100644
--- a/lang/c++/impl/json/JsonDom.hh
+++ b/lang/c++/impl/json/JsonDom.hh
@@ -76,22 +76,22 @@ public:
     explicit Entity(size_t line = 0) : type_(EntityType::Null), line_(line) {}
     // Not explicit because do want implicit conversion
     // NOLINTNEXTLINE(google-explicit-constructor)
-    Entity(Bool v, size_t line = 0) : type_(EntityType::Bool), value_(v), line_(line) {}
+    explicit Entity(Bool v, size_t line = 0) : type_(EntityType::Bool), value_(v), line_(line) {}
     // Not explicit because do want implicit conversion
     // NOLINTNEXTLINE(google-explicit-constructor)
-    Entity(Long v, size_t line = 0) : type_(EntityType::Long), value_(v), line_(line) {}
+    explicit Entity(Long v, size_t line = 0) : type_(EntityType::Long), value_(v), line_(line) {}
     // Not explicit because do want implicit conversion
     // NOLINTNEXTLINE(google-explicit-constructor)
-    Entity(Double v, size_t line = 0) : type_(EntityType::Double), value_(v), line_(line) {}
+    explicit Entity(Double v, size_t line = 0) : type_(EntityType::Double), value_(v), line_(line) {}
     // Not explicit because do want implicit conversion
     // NOLINTNEXTLINE(google-explicit-constructor)
-    Entity(const std::shared_ptr<String> &v, size_t line = 0) : type_(EntityType::String), value_(v), line_(line) {}
+    explicit Entity(const std::shared_ptr<String> &v, size_t line = 0) : type_(EntityType::String), value_(v), line_(line) {}
     // Not explicit because do want implicit conversion
     // NOLINTNEXTLINE(google-explicit-constructor)
-    Entity(const std::shared_ptr<Array> &v, size_t line = 0) : type_(EntityType::Arr), value_(v), line_(line) {}
+    explicit Entity(const std::shared_ptr<Array> &v, size_t line = 0) : type_(EntityType::Arr), value_(v), line_(line) {}
     // Not explicit because do want implicit conversion
     // NOLINTNEXTLINE(google-explicit-constructor)
-    Entity(const std::shared_ptr<Object> &v, size_t line = 0) : type_(EntityType::Obj), value_(v), line_(line) {}
+    explicit Entity(const std::shared_ptr<Object> &v, size_t line = 0) : type_(EntityType::Obj), value_(v), line_(line) {}
 
     EntityType type() const { return type_; }