diff --git a/loopy/kernel.py b/loopy/kernel.py
index 35904443aa5d509fff7da930828de2e937efb27c..a30e5194c2ff9441652647b0b30fcaf92b77b1db 100644
--- a/loopy/kernel.py
+++ b/loopy/kernel.py
@@ -817,7 +817,7 @@ class LoopKernel(Record):
                         elif opt_key == "priority":
                             priority = int(opt_value)
                         elif opt_key == "dep":
-                            insn_deps = opt_value.split(":")
+                            insn_deps = set(opt_value.split(":"))
                         else:
                             raise ValueError("unrecognized instruction option '%s'"
                                     % opt_key)