diff --git a/gcviewer/ext-mappings b/gcviewer/ext-mappings
new file mode 100644
index 0000000..97e2aaa
--- /dev/null
+++ b/gcviewer/ext-mappings
@@ -0,0 +1 @@
+*=jar
diff --git a/gcviewer/urls b/gcviewer/urls
new file mode 100644
index 0000000..dca36bb
--- /dev/null
+++ b/gcviewer/urls
@@ -0,0 +1 @@
+https://sourceforge.net/projects/gcviewer/files/gcviewer-${version}.${ext}