diff --git a/src/gflags_completions.cc b/src/gflags_completions.cc
index 3a47623..d7097ca 100644
--- a/src/gflags_completions.cc
+++ b/src/gflags_completions.cc
@@ -47,6 +47,8 @@
 //     5b) Trim most flag's descriptions to fit on a single terminal line
 
 
+#include "gflags_completions.h"
+
 #include "config.h"
 
 #include <stdio.h>
diff --git a/src/windows_port.cc b/src/windows_port.cc
index 9ccb630..b5b7194 100644
--- a/src/windows_port.cc
+++ b/src/windows_port.cc
@@ -44,6 +44,7 @@
 
 // These call the windows _vsnprintf, but always NUL-terminate.
 #if !defined(__MINGW32__) && !defined(__MINGW64__)  /* mingw already defines */
+#if !(defined(_MSC_VER) && _MSC_VER >= 1900)  /* msvc 2015 already defines */
 
 #ifdef _MSC_VER
 #  pragma warning(push)
@@ -59,8 +60,6 @@ int safe_vsnprintf(char *str, size_t size, const char *format, va_list ap) {
 #  pragma warning(pop)
 #endif
 
-#if _MSC_VER < 1900  // msvs 2015 finally includes snprintf
-
 int snprintf(char *str, size_t size, const char *format, ...) {
   int r;
   va_list ap;
@@ -70,6 +69,5 @@ int snprintf(char *str, size_t size, const char *format, ...) {
   return r;
 }
 
-#endif
-
+#endif  /* if !(defined(_MSC_VER) && _MSC_VER >= 1900)  */
 #endif  /* #if !defined(__MINGW32__) && !defined(__MINGW64__) */
diff --git a/src/windows_port.h b/src/windows_port.h
index c8ff24f..554b9c9 100644
--- a/src/windows_port.h
+++ b/src/windows_port.h
@@ -63,12 +63,14 @@
  * name vsnprintf, since windows defines that (but not snprintf (!)).
  */
 #if !defined(__MINGW32__) && !defined(__MINGW64__)  /* mingw already defines */
+#if !(defined(_MSC_VER) && _MSC_VER >= 1900)  /* msvc 2015 already defines */
 extern GFLAGS_DLL_DECL int snprintf(char *str, size_t size,
                                        const char *format, ...);
 extern int GFLAGS_DLL_DECL safe_vsnprintf(char *str, size_t size,
                                              const char *format, va_list ap);
 #define vsnprintf(str, size, format, ap)  safe_vsnprintf(str, size, format, ap)
 #define va_copy(dst, src)  (dst) = (src)
+#endif
 #endif  /* #if !defined(__MINGW32__) && !defined(__MINGW64__) */
 
 #ifdef _MSC_VER
diff --git a/test/gflags_declare_flags.cc b/test/gflags_declare_flags.cc
index dc53de5..2491686 100644
--- a/test/gflags_declare_flags.cc
+++ b/test/gflags_declare_flags.cc
@@ -3,6 +3,7 @@
 
 DECLARE_string(message); // in gflags_delcare_test.cc
 
+void print_message();
 void print_message()
 {
   std::cout << FLAGS_message << std::endl;
diff --git a/test/gflags_unittest.cc b/test/gflags_unittest.cc
index 80f7398..cc3049b 100644
--- a/test/gflags_unittest.cc
+++ b/test/gflags_unittest.cc
@@ -1485,7 +1485,7 @@ TEST(FlagsValidator, FlagSaver) {
 
 }  // unnamed namespace
 
-int main(int argc, char **argv) {
+static int main(int argc, char **argv) {
 
   // Run unit tests only if called without arguments, otherwise this program
   // is used by an "external" usage test