diff --git a/db/pdfile.cpp b/db/pdfile.cpp
index f7e60ea8268..6190c2d0cc2 100644
--- a/db/pdfile.cpp
+++ b/db/pdfile.cpp
@@ -1053,7 +1053,7 @@ boost::intmax_t dbSize( const char *database ) {
 boost::intmax_t freeSpace() {
     struct statvfs info;
     assert( !statvfs( dbpath, &info ) );
-    return info.f_bavail * info.f_frsize;
+    return boost::intmax_t( info.f_bavail ) * info.f_frsize;
 }
 #endif