diff --git a/test_common/harness/conversions.cpp b/test_common/harness/conversions.cpp
index c7731269..d52a2ac6 100644
--- a/test_common/harness/conversions.cpp
+++ b/test_common/harness/conversions.cpp
@@ -14,6 +14,7 @@
 // limitations under the License.
 //
 #include "conversions.h"
+#include <cinttypes>
 #include <limits.h>
 #include <time.h>
 #include <assert.h>
@@ -50,10 +51,10 @@ void print_type_to_string(ExplicitType type, void *data, char *string)
         case kInt: sprintf(string, "%d", *((cl_int *)data)); return;
         case kUInt:
         case kUnsignedInt: sprintf(string, "%u", *((cl_uint *)data)); return;
-        case kLong: sprintf(string, "%lld", *((cl_long *)data)); return;
+        case kLong: sprintf(string, "%" PRId64 "", *((cl_long *)data)); return;
         case kULong:
         case kUnsignedLong:
-            sprintf(string, "%llu", *((cl_ulong *)data));
+            sprintf(string, "%" PRIu64 "", *((cl_ulong *)data));
             return;
         case kFloat: sprintf(string, "%f", *((cl_float *)data)); return;
         case kHalf: sprintf(string, "half"); return;
diff --git a/test_common/harness/imageHelpers.cpp b/test_common/harness/imageHelpers.cpp
index 3dbdffa0..f1694e88 100644
--- a/test_common/harness/imageHelpers.cpp
+++ b/test_common/harness/imageHelpers.cpp
@@ -23,6 +23,7 @@
 #include <malloc.h>
 #endif
 #include <algorithm>
+#include <cinttypes>
 #include <iterator>
 #if !defined(_WIN32)
 #include <cmath>
@@ -421,7 +422,7 @@ void print_first_pixel_difference_error(size_t where, const char *sourcePixel,
               (int)thirdDim, (int)imageInfo->rowPitch,
               (int)imageInfo->rowPitch
                   - (int)imageInfo->width * (int)pixel_size);
-    log_error("Failed at column: %ld   ", where);
+    log_error("Failed at column: %zu   ", where);
 
     switch (pixel_size)
     {
@@ -454,7 +455,7 @@ void print_first_pixel_difference_error(size_t where, const char *sourcePixel,
                 ((cl_ushort *)destPixel)[1], ((cl_ushort *)destPixel)[2]);
             break;
         case 8:
-            log_error("*0x%16.16llx vs. 0x%16.16llx\n",
+            log_error("*0x%16.16" PRIx64 " vs. 0x%16.16" PRIx64 "\n",
                       ((cl_ulong *)sourcePixel)[0], ((cl_ulong *)destPixel)[0]);
             break;
         case 12:
@@ -473,7 +474,7 @@ void print_first_pixel_difference_error(size_t where, const char *sourcePixel,
                       ((cl_uint *)destPixel)[2], ((cl_uint *)destPixel)[3]);
             break;
         default:
-            log_error("Don't know how to print pixel size of %ld\n",
+            log_error("Don't know how to print pixel size of %zu\n",
                       pixel_size);
             break;
     }
diff --git a/test_common/harness/propertyHelpers.cpp b/test_common/harness/propertyHelpers.cpp
index e368f9b6..6a10c076 100644
--- a/test_common/harness/propertyHelpers.cpp
+++ b/test_common/harness/propertyHelpers.cpp
@@ -19,6 +19,7 @@
 #include <assert.h>
 
 #include <algorithm>
+#include <cinttypes>
 #include <vector>
 
 static bool findProperty(const std::vector<cl_properties>& props,
@@ -97,16 +98,16 @@ int compareProperties(const std::vector<cl_properties>& queried,
 
             if (!found)
             {
-                log_error("ERROR: expected property 0x%llx not found!\n",
+                log_error("ERROR: expected property 0x%" PRIx64 " not found!\n",
                           check_prop);
                 return TEST_FAIL;
             }
             else if (check_value != queried_value)
             {
-                log_error(
-                    "ERROR: mis-matched value for property 0x%llx: wanted "
-                    "0x%llx, got 0x%llx\n",
-                    check_prop, check_value, queried_value);
+                log_error("ERROR: mis-matched value for property 0x%" PRIx64
+                          ": wanted "
+                          "0x%" PRIx64 ", got 0x%" PRIx64 "\n",
+                          check_prop, check_value, queried_value);
                 return TEST_FAIL;
             }
         }
diff --git a/test_common/harness/testHarness.cpp b/test_common/harness/testHarness.cpp
index d07d982c..a309f53d 100644
--- a/test_common/harness/testHarness.cpp
+++ b/test_common/harness/testHarness.cpp
@@ -1198,7 +1198,7 @@ cl_platform_id getPlatformFromDevice(cl_device_id deviceID)
 
 void PrintArch(void)
 {
-    vlog("sizeof( void*) = %ld\n", sizeof(void *));
+    vlog("sizeof( void*) = %zu\n", sizeof(void *));
 #if defined(__ppc__)
     vlog("ARCH:\tppc\n");
 #elif defined(__ppc64__)