diff --git a/src/crwimage_int.cpp b/src/crwimage_int.cpp
index b1c9ac28..923cd2c4 100644
--- a/src/crwimage_int.cpp
+++ b/src/crwimage_int.cpp
@@ -127,8 +127,6 @@ const CrwSubDir CrwMap::crwSubDir_[] = {
     {0x2807, 0x300a}, {0x2804, 0x300a}, {0x300a, 0x0000}, {0x0000, 0xffff},
 };
 
-const char CiffHeader::signature_[] = "HEAPCCDR";
-
 CiffDirectory::~CiffDirectory() {
   for (auto&& component : components_) {
     delete component;
diff --git a/src/crwimage_int.hpp b/src/crwimage_int.hpp
index 15917e34..eb326bcc 100644
--- a/src/crwimage_int.hpp
+++ b/src/crwimage_int.hpp
@@ -480,7 +480,7 @@ class CiffHeader {
 
  private:
   // DATA
-  static const char signature_[];  //!< Canon CRW signature "HEAPCCDR"
+  static constexpr auto signature_ = "HEAPCCDR";  //!< Canon CRW signature
 
   std::unique_ptr<CiffDirectory> pRootDir_;  //!< Pointer to the root directory
   ByteOrder byteOrder_ = littleEndian;       //!< Applicable byte order