diff --git a/posix.h b/posix.h
index cbe2466e..16cf952a 100644
--- a/posix.h
+++ b/posix.h
@@ -61,9 +61,9 @@
 # define FMT_SYSTEM(call) call
 # ifdef _WIN32
 // Fix warnings about deprecated symbols.
-#  define FMT_POSIX_CALL(call) ::_##call
+#  define FMT_POSIX_CALL(call) (::_##call)
 # else
-#  define FMT_POSIX_CALL(call) (::call)
+#  define FMT_POSIX_CALL(call) ::call
 # endif
 #endif
 
diff --git a/test/posix-test.h b/test/posix-test.h
index 4768cb94..a43ce1ef 100644
--- a/test/posix-test.h
+++ b/test/posix-test.h
@@ -39,7 +39,7 @@ struct stat;
 
 namespace test {
 
-#ifndef _WIN32
+#if !defined(_WIN32) || defined(__MINGW32__)
 // Size type for read and write.
 typedef size_t size_t;
 typedef ssize_t ssize_t;