diff --git a/test/hei_user_defines.hpp b/test/hei_user_defines.hpp
index c84981b..08ddda9 100644
--- a/test/hei_user_defines.hpp
+++ b/test/hei_user_defines.hpp
@@ -7,6 +7,7 @@
  */
 
 #include <assert.h>
+#include <inttypes.h>
 #include <stdio.h>
 
 #define HEI_INF(...)                                                           \
diff --git a/test/simulator/user_interface.cpp b/test/simulator/user_interface.cpp
index 2bcc2af..0b8b6ef 100644
--- a/test/simulator/user_interface.cpp
+++ b/test/simulator/user_interface.cpp
@@ -50,8 +50,9 @@
         // END temporary code
         default:
             rc = RC_REG_ACCESS_FAILURE;
-            HEI_ERR("registerRead(%p,%p,%lx,%lx,%lx)", i_chip.getChip(),
-                    o_buffer, io_bufSize, i_regType, i_address);
+            HEI_ERR("registerRead(%p,%p,%" PRIu64 ",%" PRIx64 ",%" PRIx64 ")",
+                    i_chip.getChip(), o_buffer, (uint64_t)io_bufSize, i_regType,
+                    i_address);
     }
 
     return rc;
@@ -74,8 +75,9 @@
         // TODO: add cases for REG_TYPE_SCOM and REG_TYPE_ID_SCOM
         default:
             rc = RC_REG_ACCESS_FAILURE;
-            HEI_ERR("registerWrite(%p,%p,%lx,%lx,%lx)", i_chip.getChip(),
-                    i_buffer, io_bufSize, i_regType, i_address);
+            HEI_ERR("registerWrite(%p,%p,%" PRIu64 ",%" PRIx64 ",%" PRIx64 ")",
+                    i_chip.getChip(), i_buffer, (uint64_t)io_bufSize, i_regType,
+                    i_address);
     }
 
     return rc;