diff --git a/dev/tests/filesystem.lua b/dev/tests/filesystem.lua
index 38e7c4a04..cb5a052ac 100644
--- a/dev/tests/filesystem.lua
+++ b/dev/tests/filesystem.lua
@@ -1,3 +1,9 @@
+debug.log("file extension")
+asserts.equals(nil, file.ext("config:test"))
+asserts.equals("cfg", file.ext("config:test.cfg"))
+asserts.equals("gz", file.ext("config:test.cfg.gz"))
+asserts.equals("config:test.cfg", file.remove_ext("config:test.cfg.gz"))
+
 debug.log("check initial state")
 assert(file.exists("config:"))
 
diff --git a/res/modules/internal/extensions/file.lua b/res/modules/internal/extensions/file.lua
index d308eda9c..6d5dc30ba 100644
--- a/res/modules/internal/extensions/file.lua
+++ b/res/modules/internal/extensions/file.lua
@@ -8,7 +8,7 @@ function file.stem(path)
 end
 
 function file.ext(path)
-    return path:match("%.([^:/\\]+)$")
+    return path:match("[^:/\\.]%.([^.:/\\]+)$")
 end
 
 function file.prefix(path)
@@ -24,7 +24,11 @@ function file.parent(path)
 end
 
 function file.remove_ext(path)
-    return string.format("%s/%s", file.parent(path), file.stem(path))
+    local ext = file.ext(path)
+    if not ext then
+        return path
+    end
+    return path:sub(1, -#ext - 2)
 end
 
 function file.path(path)