diff --git a/tests/Basic/Basic.h b/tests/Basic/Basic.h
index d99af035..ba8a3854 100644
--- a/tests/Basic/Basic.h
+++ b/tests/Basic/Basic.h
@@ -1,10 +1,4 @@
-#if defined(_MSC_VER)
-#define DLL_API __declspec(dllexport)
-#else
-#define DLL_API
-#endif
-
-#define CS_OUT
+#include "../Tests.h"
 
 class DLL_API Foo
 {
diff --git a/tests/CLITemp/CLITemp.h b/tests/CLITemp/CLITemp.h
index c507dbf5..15431f98 100644
--- a/tests/CLITemp/CLITemp.h
+++ b/tests/CLITemp/CLITemp.h
@@ -1,8 +1,4 @@
-#if defined(_MSC_VER)
-#define DLL_API __declspec(dllexport)
-#else
-#define DLL_API
-#endif
+#include "../Tests.h"
 
 // Tests for C++ types
 struct DLL_API Types
diff --git a/tests/CSharpTemp/CSharpTemp.h b/tests/CSharpTemp/CSharpTemp.h
index 1f967826..f7365de4 100644
--- a/tests/CSharpTemp/CSharpTemp.h
+++ b/tests/CSharpTemp/CSharpTemp.h
@@ -1,8 +1,4 @@
-#if defined(_MSC_VER)
-#define DLL_API __declspec(dllexport)
-#else
-#define DLL_API
-#endif
+#include "../Tests.h"
 
 class DLL_API Foo
 {
diff --git a/tests/STL/STL.h b/tests/STL/STL.h
index c0b7a337..b67e5b2e 100644
--- a/tests/STL/STL.h
+++ b/tests/STL/STL.h
@@ -1,9 +1,4 @@
-#if defined(_MSC_VER)
-#define DLL_API __declspec(dllexport)
-#else
-#define DLL_API
-#endif
-
+#include "../Tests.h"
 #include <vector>
 
 struct DLL_API TestVectors
diff --git a/tests/Tests.h b/tests/Tests.h
new file mode 100644
index 00000000..eec3d665
--- /dev/null
+++ b/tests/Tests.h
@@ -0,0 +1,9 @@
+#pragma once
+
+#if defined(_MSC_VER)
+#define DLL_API __declspec(dllexport)
+#else
+#define DLL_API
+#endif
+
+#define CS_OUT
\ No newline at end of file
diff --git a/tests/UTF16/UTF16.h b/tests/UTF16/UTF16.h
index 6893aabc..799a38c9 100644
--- a/tests/UTF16/UTF16.h
+++ b/tests/UTF16/UTF16.h
@@ -1,8 +1,4 @@
-#if defined(_MSC_VER)
-#define DLL_API __declspec(dllexport)
-#else
-#define DLL_API
-#endif
+#include "../Tests.h"
 
 class DLL_API Foo
 {
diff --git a/tests/VTables/VTables.h b/tests/VTables/VTables.h
index dae69f35..bc943312 100644
--- a/tests/VTables/VTables.h
+++ b/tests/VTables/VTables.h
@@ -1,8 +1,4 @@
-#if defined(_MSC_VER)
-#define DLL_API __declspec(dllexport)
-#else
-#define DLL_API
-#endif
+#include "../Tests.h"
 
 class DLL_API Foo
 {