diff --git a/src/chip_data/hei_chip_data.cpp b/src/chip_data/hei_chip_data.cpp
index 8b73696..0c61985 100644
--- a/src/chip_data/hei_chip_data.cpp
+++ b/src/chip_data/hei_chip_data.cpp
@@ -8,10 +8,6 @@
 
 //------------------------------------------------------------------------------
 
-using FileKeyword_t = uint64_t;
-
-constexpr FileKeyword_t KW_CHIPDATA = 0x4348495044415441; // "CHIPDATA" ASCII
-
 using SectionKeyword_t = uint32_t;
 
 constexpr SectionKeyword_t KW_REGS = 0x52454753; // "REGS" ASCII
diff --git a/src/hei_isolation_data.hpp b/src/hei_isolation_data.hpp
index df07e05..93ec5b8 100644
--- a/src/hei_isolation_data.hpp
+++ b/src/hei_isolation_data.hpp
@@ -45,7 +45,7 @@
     }
 
     /** @brief Allows access to the signature list. */
-    const std::vector<Signature>& getSignatureList()
+    const std::vector<Signature>& getSignatureList() const
     {
         return iv_sigLists;
     }
diff --git a/src/hei_types.hpp b/src/hei_types.hpp
index e70edd4..b006a1c 100644
--- a/src/hei_types.hpp
+++ b/src/hei_types.hpp
@@ -178,4 +178,12 @@
     // clang-format on
 };
 
+/**
+ * Each Chip Data File will begin with a keyword signafying it is a Chip Data
+ * File.
+ */
+using FileKeyword_t = uint64_t;
+
+constexpr FileKeyword_t KW_CHIPDATA = 0x4348495044415441; // "CHIPDATA" ASCII
+
 } // end namespace libhei