diff --git a/src/isolator/hei_isolator.cpp b/src/isolator/hei_isolator.cpp
index cb254aa..d932659 100644
--- a/src/isolator/hei_isolator.cpp
+++ b/src/isolator/hei_isolator.cpp
@@ -19,8 +19,8 @@
     ReturnCode rc;
 
     // BEGIN temporary code
-    HEI_INF("Isolator::initialize(%p,%lu,%d)", i_buffer, i_bufferSize,
-            i_forceInit);
+    HEI_INF("Isolator::initialize(%p,%" PRIu64 ",%d)", i_buffer,
+            (uint64_t)i_bufferSize, i_forceInit);
 
     auto& scom_fw    = Flyweight<ScomRegister>::getSingleton();
     auto& idScom_fw  = Flyweight<IdScomRegister>::getSingleton();
diff --git a/src/util/hei_bit_string.cpp b/src/util/hei_bit_string.cpp
index 16713ec..8fc0776 100644
--- a/src/util/hei_bit_string.cpp
+++ b/src/util/hei_bit_string.cpp
@@ -15,9 +15,9 @@
 //##############################################################################
 
 // number of bits in a uint64_t
-constexpr uint64_t BitString::UINT64_BIT_LEN = sizeof(uint64_t) * 8;
+const uint64_t BitString::UINT64_BIT_LEN = sizeof(uint64_t) * 8;
 // number of bits in a uint8_t
-constexpr uint64_t BitString::UINT8_BIT_LEN = sizeof(uint8_t) * 8;
+const uint64_t BitString::UINT8_BIT_LEN = sizeof(uint8_t) * 8;
 
 //------------------------------------------------------------------------------