diff --git a/sc2/src/port.c b/sc2/src/port.c
index 622b96b69..857ec1c61 100644
--- a/sc2/src/port.c
+++ b/sc2/src/port.c
@@ -21,8 +21,12 @@
  */
 
 #include <ctype.h>
+#include "errno.h"
 #include <stdlib.h>
 #include <string.h>
+#ifndef HAVE_READDIR_R
+#	include <dirent.h>
+#endif
 #include "port.h"
 
 #ifndef HAVE_STRUPR
@@ -78,4 +82,31 @@ setenv (const char *name, const char *value, int overwrite)
 }
 #endif
 
+#ifndef HAVE_READDIR_R
+// NB. This function calls readdir() directly, and as such has the same
+//     reentrance issues as that function. For the purposes of UQM it will
+//     do though.
+//     Note the POSIX requires that "The pointer returned by readdir()
+//     points to data which may be overwritten by another call to
+//     readdir( ) on the same directory stream. This data is not
+//     overwritten by another call to readdir() on a different directory
+//     stream."
+// NB. This function makes an extra copy of the dirent and will hence be
+//     slower than a direct call to readdir() or readdir_r().
+int
+readdir_r(DIR *dirp, struct dirent *entry, struct dirent **result) {
+	struct dirent *readdir_entry;
+
+	readdir_entry = readdir(dirp);
+	if (readdir_entry == NULL) {
+		*result = NULL;
+		return errno;
+	}
+
+	*entry = *readdir_entry;
+	*result = entry;
+	return 0;
+}
+#endif
+
 
diff --git a/sc2/src/port.h b/sc2/src/port.h
index aea93f0fd..01cc995b5 100644
--- a/sc2/src/port.h
+++ b/sc2/src/port.h
@@ -19,6 +19,11 @@
 char *strupr (char *str);
 #endif
 
+#ifndef HAVE_READDIR_R
+#	include <dirent.h>
+int readdir_r(DIR *dirp, struct dirent *entry, struct dirent **result);
+#endif
+
 
 // Compilation related
 #ifdef _MSC_VER