diff --git a/test/gtest-extra-test.cc b/test/gtest-extra-test.cc
index daf5fe3e..53e72e1e 100644
--- a/test/gtest-extra-test.cc
+++ b/test/gtest-extra-test.cc
@@ -154,12 +154,12 @@ TEST(FileTest, DefaultCtor) {
 // Checks if the file is open by reading one character from it.
 bool IsOpen(int fd) {
   char buffer;
-  return read(fd, &buffer, 1) == 1;
+  return FMT_POSIX(read(fd, &buffer, 1)) == 1;
 }
 
 bool IsClosedInternal(int fd) {
   char buffer;
-  std::streamsize result = read(fd, &buffer, 1);
+  std::streamsize result = FMT_POSIX(read(fd, &buffer, 1));
   return result == -1 && errno == EBADF;
 }
 
@@ -248,7 +248,7 @@ TEST(FileTest, DtorCloseError) {
   // The close function must be called inside EXPECT_STDERR, otherwise
   // the system may allocate freed file descriptor when redirecting the
   // output in EXPECT_STDERR.
-  EXPECT_STDERR(close(f->descriptor()); delete f,
+  EXPECT_STDERR(FMT_POSIX(close(f->descriptor())); delete f,
     FormatSystemErrorMessage(EBADF, "cannot close file") + "\n");
 }
 
diff --git a/test/gtest-extra.cc b/test/gtest-extra.cc
index bc9003b7..fecbb79a 100644
--- a/test/gtest-extra.cc
+++ b/test/gtest-extra.cc
@@ -165,7 +165,7 @@ std::string OutputRedirector::Read() {
   // Restore output.
   if (std::fflush(file_) != 0)
     fmt::ThrowSystemError(errno, "cannot flush stream");
-  saved_.dup2(fileno(file_));
+  saved_.dup2(FMT_POSIX(fileno(file_)));
 
   // Read everything from the pipe.
   std::string content;
@@ -174,7 +174,7 @@ std::string OutputRedirector::Read() {
   std::streamsize count = 0;
   do {
     count = read_end_.read(buffer, BUFFER_SIZE);
-    content.append(buffer, count);
+    content.append(buffer, static_cast<std::size_t>(count));
   } while (count != 0);
   return content;
 }