diff --git a/tests/unittests/test-int2dec.cpp b/tests/unittests/test-int2dec.cpp
index 25e57128fb..96d532c5df 100644
--- a/tests/unittests/test-int2dec.cpp
+++ b/tests/unittests/test-int2dec.cpp
@@ -1,7 +1,11 @@
 #include <gtest/gtest.h>
 
 #include <limits>
+
+#ifndef NOMINMAX
 #define NOMINMAX
+#endif /* #ifndef NOMINMAX */
+
 #include <Windows.h>
 #include <tchar.h>
 #include "basis/primitive.h"
diff --git a/tests/unittests/test-is_mailaddress.cpp b/tests/unittests/test-is_mailaddress.cpp
index 3ad214b57e..77836a7b42 100644
--- a/tests/unittests/test-is_mailaddress.cpp
+++ b/tests/unittests/test-is_mailaddress.cpp
@@ -24,7 +24,10 @@
 */
 #include <gtest/gtest.h>
 
+#ifndef NOMINMAX
 #define NOMINMAX
+#endif /* #ifndef NOMINMAX */
+
 #include <tchar.h>
 #include <wchar.h>
 #include <assert.h>