diff --git a/dep/libchdr/include/libchdr/chd.h b/dep/libchdr/include/libchdr/chd.h
index 0beed4903..4c95439ad 100644
--- a/dep/libchdr/include/libchdr/chd.h
+++ b/dep/libchdr/include/libchdr/chd.h
@@ -389,11 +389,13 @@ CHD_EXPORT void chd_close(chd_file *chd);
 /* return the associated core_file */
 CHD_EXPORT core_file *chd_core_file(chd_file *chd);
 
+/* return the overall size of a CHD, and any of its parents */
+CHD_EXPORT UINT64 chd_get_compressed_size(chd_file* chd);
+
 /* return an error string for the given CHD error */
 CHD_EXPORT const char *chd_error_string(chd_error err);
 
 
-
 /* ----- CHD header management ----- */
 
 /* return a pointer to the extracted CHD header data */
diff --git a/dep/libchdr/src/libchdr_chd.c b/dep/libchdr/src/libchdr_chd.c
index 8c65d7459..65f1415bf 100644
--- a/dep/libchdr/src/libchdr_chd.c
+++ b/dep/libchdr/src/libchdr_chd.c
@@ -1952,6 +1952,14 @@ CHD_EXPORT core_file *chd_core_file(chd_file *chd)
 	return chd->file;
 }
 
+CHD_EXPORT UINT64 chd_get_compressed_size(chd_file *chd)
+{
+	UINT64 size = chd->file->fsize(chd->file);
+	if (chd->parent)
+		size += chd_get_compressed_size(chd->parent);
+	return size;
+}
+
 /*-------------------------------------------------
     chd_error_string - return an error string for
     the given CHD error