diff --git a/src/klotski/common_code/common_code.h b/src/klotski/common_code/common_code.h
index ac65413..fe0a8c0 100644
--- a/src/klotski/common_code/common_code.h
+++ b/src/klotski/common_code/common_code.h
@@ -68,8 +68,8 @@ namespace klotski {
         static bool check(uint64_t common_code);
 
         /// Operators of CommonCode
-        constexpr operator uint64_t() const { return code; }
         bool operator==(const CommonCode &common_code) const;
+        constexpr explicit operator uint64_t() const { return code; }
         friend std::ostream& operator<<(std::ostream &out, const CommonCode &self);
 
         /// Export functions
diff --git a/src/klotski/raw_code/raw_code.h b/src/klotski/raw_code/raw_code.h
index 9502c9a..5273a81 100644
--- a/src/klotski/raw_code/raw_code.h
+++ b/src/klotski/raw_code/raw_code.h
@@ -50,7 +50,7 @@ namespace klotski {
 
         /// Operators of RawCode
         bool operator==(const RawCode &raw_code) const;
-        constexpr operator uint64_t() const { return code; }
+        constexpr explicit operator uint64_t() const { return code; }
         friend std::ostream& operator<<(std::ostream &out, const RawCode &self);
 
         /// Export functions
diff --git a/src/klotski/short_code/short_code.h b/src/klotski/short_code/short_code.h
index 529589b..2bf5156 100644
--- a/src/klotski/short_code/short_code.h
+++ b/src/klotski/short_code/short_code.h
@@ -40,8 +40,8 @@ namespace klotski {
         static bool check(uint32_t short_code);
 
         /// Operators of ShortCode
-        constexpr operator uint32_t() const { return code; }
         bool operator==(const ShortCode &short_code) const;
+        constexpr explicit operator uint32_t() const { return code; }
         friend std::ostream& operator<<(std::ostream &out, const ShortCode &self);
 
         /// Export functions