diff --git a/aegisub/libaegisub/common/util.cpp b/aegisub/libaegisub/common/util.cpp
index 513e0ab2e..52b76220f 100644
--- a/aegisub/libaegisub/common/util.cpp
+++ b/aegisub/libaegisub/common/util.cpp
@@ -38,8 +38,9 @@ namespace agi {
 
 
 void str_lower(std::string &str) {
+	std::locale loc;
 	for (size_t i=0; i < str.length(); ++i) {
-		str[i] = std::tolower(str[i]);
+		str[i] = std::tolower(str[i], loc);
 	}
 }
 
@@ -54,23 +55,5 @@ int strtoi(std::string &str) {
 }
 
 
-uint64_t freespace(std::string &path, PathType type) {
-	struct statfs fs;
-	std::string check(path);
-
-	if (type == TypeFile)
-		check.assign(DirName(path));
-
-	acs::CheckDirRead(check);
-
-	if ((statfs(check.c_str(), &fs)) == 0) {
-		return fs.f_bsize * fs.f_bavail;
-	} else {
-		/// @todo We need a collective set of exceptions for ENOTDIR, EIO etc.
-		throw("Failed getting free space");
-	}
-}
-
-
 	} // namespace util
 } // namespace agi
diff --git a/aegisub/libaegisub/lagi_pre.h b/aegisub/libaegisub/lagi_pre.h
index ee51e5e7d..164d61f37 100644
--- a/aegisub/libaegisub/lagi_pre.h
+++ b/aegisub/libaegisub/lagi_pre.h
@@ -11,7 +11,6 @@
 #include <string.h>
 #include <sys/stat.h>
 #include <sys/param.h>
-#include <sys/mount.h>
 #ifdef HAVE_SYS_TIME_H
 #  include <sys/time.h>
 #else
@@ -25,6 +24,11 @@
 #include <io.h>
 #endif
 
+// Unix C
+#ifndef _WIN32
+#  include <sys/mount.h> // yep, this exists on MacOS X as well, but not on Windows.
+#endif
+
 // Common C++
 #include <deque>
 #include <climits>
diff --git a/aegisub/libaegisub/unix/util.cpp b/aegisub/libaegisub/unix/util.cpp
index 58845ff59..ecc8bb289 100644
--- a/aegisub/libaegisub/unix/util.cpp
+++ b/aegisub/libaegisub/unix/util.cpp
@@ -59,5 +59,23 @@ void time_log(timeval &tv) {
 	gettimeofday(&tv, (struct timezone *)NULL);
 }
 
+uint64_t freespace(std::string &path, PathType type) {
+	struct statfs fs;
+	std::string check(path);
+
+	if (type == TypeFile)
+		check.assign(DirName(path));
+
+	acs::CheckDirRead(check);
+
+	if ((statfs(check.c_str(), &fs)) == 0) {
+		return fs.f_bsize * fs.f_bavail;
+	} else {
+		/// @todo We need a collective set of exceptions for ENOTDIR, EIO etc.
+		throw("Failed getting free space");
+	}
+}
+
+
 	} // namespace io
 } // namespace agi