diff --git a/dtool/Config.Linux.pp b/dtool/Config.Linux.pp
index 0a8c8c152e..88a379657b 100644
--- a/dtool/Config.Linux.pp
+++ b/dtool/Config.Linux.pp
@@ -133,6 +133,9 @@
 // Do we have RTTI (and <typeinfo>)?
 #define HAVE_RTTI 1
 
+// We need 64-bit file i/o
+#define __USE_LARGEFILE64 1
+
 // Must global operator new and delete functions throw exceptions?
 #define GLOBAL_OPERATOR_NEW_EXCEPTIONS 1
 
diff --git a/dtool/LocalSetup.pp b/dtool/LocalSetup.pp
index ce3c51d5e4..f311ae7875 100644
--- a/dtool/LocalSetup.pp
+++ b/dtool/LocalSetup.pp
@@ -468,6 +468,9 @@ $[cdefine HAVE_LINUX_NATIVE_THREADS]
 /* Is the code being compiled with the Tau profiler's instrumentor? */
 $[cdefine USE_TAU]
 
+/* Define if needed to have 64-bit file i/o */
+$[cdefine __USE_LARGEFILE64]
+
 /* Must global operator new and delete functions throw exceptions? */
 $[cdefine GLOBAL_OPERATOR_NEW_EXCEPTIONS]