diff --git a/flang-rt/lib/runtime/command.cpp b/flang-rt/lib/runtime/command.cpp
index 6b5d7722d9eb..f0f4e8bf64e9 100644
--- a/flang-rt/lib/runtime/command.cpp
+++ b/flang-rt/lib/runtime/command.cpp
@@ -23,11 +23,9 @@
 #define unlink _unlink
 #define PATH_MAX MAX_PATH
 
-#ifdef _MSC_VER
 // On Windows GetCurrentProcessId returns a DWORD aka uint32_t
 #include <processthreadsapi.h>
 inline pid_t getpid() { return GetCurrentProcessId(); }
-#endif
 #else
 #include <unistd.h> //getpid() unlink()
 
diff --git a/flang-rt/lib/runtime/environment.cpp b/flang-rt/lib/runtime/environment.cpp
index be4f7308ab02..aa3daf8baf89 100644
--- a/flang-rt/lib/runtime/environment.cpp
+++ b/flang-rt/lib/runtime/environment.cpp
@@ -16,7 +16,9 @@
 #include <limits>
 
 #ifdef _WIN32
+#ifdef _MSC_VER
 extern char **_environ;
+#endif
 #elif defined(__FreeBSD__)
 // FreeBSD has environ in crt rather than libc. Using "extern char** environ"
 // in the code of a shared library makes it fail to link with -Wl,--no-undefined
diff --git a/flang/include/flang/Common/windows-include.h b/flang/include/flang/Common/windows-include.h
index 01bc6fc9eb94..1263768e9733 100644
--- a/flang/include/flang/Common/windows-include.h
+++ b/flang/include/flang/Common/windows-include.h
@@ -20,7 +20,9 @@
 
 // Target Windows 2000 and above. This is needed for newer Windows API
 // functions, e.g. GetComputerNameExA()
+#ifndef _WIN32_WINNT
 #define _WIN32_WINNT 0x0500
+#endif
 
 #include <windows.h>