diff --git a/artiq/language/units.py b/artiq/language/units.py
index 83f1133a8..8c5266c74 100644
--- a/artiq/language/units.py
+++ b/artiq/language/units.py
@@ -18,3 +18,4 @@ _register_unit("s", "pnum_")
 _register_unit("Hz", "_kMG")
 _register_unit("dB", "_")
 _register_unit("V", "um_k")
+_register_unit("A", "um_")