diff --git a/src/support/filetools.cpp b/src/support/filetools.cpp
index 310e621e17..657343fb93 100644
--- a/src/support/filetools.cpp
+++ b/src/support/filetools.cpp
@@ -1065,7 +1065,7 @@ cmd_ret const runCommand(string const & cmd)
 				0, 0, &startup, &process)) {
 
 			CloseHandle(process.hThread);
-			int fno = _open_osfhandle((long)in, _O_RDONLY);
+			int fno = _open_osfhandle(static_cast<intptr_t>(in), _O_RDONLY);
 			CloseHandle(out);
 			inf = _fdopen(fno, "r");
 		}
diff --git a/src/support/os_win32.cpp b/src/support/os_win32.cpp
index 292555d6c7..a6e5da7c5a 100644
--- a/src/support/os_win32.cpp
+++ b/src/support/os_win32.cpp
@@ -569,7 +569,7 @@ bool autoOpenFile(string const & filename, auto_open_mode const mode,
 
 	// reference: http://msdn.microsoft.com/en-us/library/bb762153.aspx
 	char const * action = (mode == VIEW) ? "open" : "edit";
-	bool success = reinterpret_cast<int>(ShellExecute(NULL, action,
+	bool success = reinterpret_cast<intptr_t>(ShellExecute(NULL, action,
 		to_local8bit(from_utf8(filename)).c_str(), NULL, NULL, 1)) > 32;
 
 	if (!path.empty() && !lyxrc.texinputs_prefix.empty()) {