diff --git a/test/assert-test.cc b/test/assert-test.cc
index 3a9c7ace..87bc82e7 100644
--- a/test/assert-test.cc
+++ b/test/assert-test.cc
@@ -1,5 +1,5 @@
 /*
- Tests of custom gtest assertions.
+ Tests of custom Google Test assertions.
 
  Copyright (c) 2012-2014, Victor Zverovich
  All rights reserved.
@@ -25,7 +25,7 @@
  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include "format-test.h"
+#include "gtest-extra.h"
 
 #include <stdexcept>
 #include <gtest/gtest-spi.h>
diff --git a/test/format-test.cc b/test/format-test.cc
index af466051..f9f9ff7c 100644
--- a/test/format-test.cc
+++ b/test/format-test.cc
@@ -25,8 +25,6 @@
  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include "format-test.h"
-
 #include <cctype>
 #include <cfloat>
 #include <climits>
@@ -74,6 +72,7 @@ int open(const char *path, int oflag, int pmode) {
 #endif
 
 #include "format.h"
+#include "gtest-extra.h"
 
 #include <stdint.h>
 
diff --git a/test/format-test.h b/test/gtest-extra.h
similarity index 96%
rename from test/format-test.h
rename to test/gtest-extra.h
index 73b8b799..36852982 100644
--- a/test/format-test.h
+++ b/test/gtest-extra.h
@@ -1,5 +1,5 @@
 /*
- Formatting library tests.
+ Custom Google Test assertions.
 
  Copyright (c) 2012-2014, Victor Zverovich
  All rights reserved.
@@ -25,6 +25,9 @@
  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+#ifndef FMT_GTEST_EXTRA_H
+#define FMT_GTEST_EXTRA_H
+
 #include <gtest/gtest.h>
 
 #define FMT_TEST_THROW_(statement, expected_exception, expected_message, fail) \
@@ -65,3 +68,5 @@
 #define EXPECT_THROW_MSG(statement, expected_exception, expected_message) \
   FMT_TEST_THROW_(statement, expected_exception, \
       expected_message, GTEST_NONFATAL_FAILURE_)
+
+#endif  // FMT_GTEST_EXTRA_H