diff --git a/tests/datetime/datetimetest.cpp b/tests/datetime/datetimetest.cpp
index 9322fe4ef2..90ec18c939 100644
--- a/tests/datetime/datetimetest.cpp
+++ b/tests/datetime/datetimetest.cpp
@@ -721,7 +721,7 @@ void DateTimeTestCase::TestTimeFormat()
             {
                 // conversion failed - should it have?
                 WX_ASSERT_MESSAGE(
-                    ("Test #%lu failed: failed to parse \"%s\"", n, s),
+                    ("Test #%u failed: failed to parse \"%s\"", n, s),
                     kind == CompareNone
                 );
             }
@@ -735,7 +735,7 @@ void DateTimeTestCase::TestTimeFormat()
                     result++;
 
                 WX_ASSERT_MESSAGE(
-                    ("Test #%lu failed: \"%s\" was left unparsed in \"%s\"",
+                    ("Test #%u failed: \"%s\" was left unparsed in \"%s\"",
                      n, result, s),
                     !*result
                 );
diff --git a/tests/strings/vararg.cpp b/tests/strings/vararg.cpp
index f1a3e54ff6..a5677c6c68 100644
--- a/tests/strings/vararg.cpp
+++ b/tests/strings/vararg.cpp
@@ -177,9 +177,9 @@ void VarArgTestCase::RepeatedPrintf()
     *p = 'i';
 
     wxString s;
-    s = wxString::Format("buffer %s, len %d", buffer, wxStrlen(buffer));
+    s = wxString::Format("buffer %s, len %d", buffer, (int)wxStrlen(buffer));
     CPPUNIT_ASSERT_EQUAL("buffer hi, len 2", s);
 
-    s = wxString::Format("buffer %s, len %d", buffer, wxStrlen(buffer));
+    s = wxString::Format("buffer %s, len %d", buffer, (int)wxStrlen(buffer));
     CPPUNIT_ASSERT_EQUAL("buffer hi, len 2", s);
 }