diff --git a/src/CryConfig.h b/src/CryConfig.h
index 0a3cfec7..1a75b5d2 100644
--- a/src/CryConfig.h
+++ b/src/CryConfig.h
@@ -10,7 +10,7 @@ namespace cryfs {
 
 class CryConfig {
 public:
-  CryConfig(const boost::filesystem::path &configfile);
+  explicit CryConfig(const boost::filesystem::path &configfile);
   virtual ~CryConfig();
 
   const std::string &RootBlob() const;
diff --git a/src/CryOpenFile.h b/src/CryOpenFile.h
index 53195f77..8efcaf6b 100644
--- a/src/CryOpenFile.h
+++ b/src/CryOpenFile.h
@@ -11,7 +11,7 @@ class FileBlob;
 
 class CryOpenFile: public fspp::OpenFile {
 public:
-  CryOpenFile(std::unique_ptr<FileBlob> fileBlob);
+  explicit CryOpenFile(std::unique_ptr<FileBlob> fileBlob);
   virtual ~CryOpenFile();
 
   void stat(struct ::stat *result) const override;