diff --git a/src/syndicate/membranes.nim b/src/syndicate/membranes.nim
index 75d24ef..a1ba502 100644
--- a/src/syndicate/membranes.nim
+++ b/src/syndicate/membranes.nim
@@ -18,24 +18,20 @@ type
     oid: Oid
     `ref`: Ref
     count: int
-    when not defined(release):
-      mem: Membrane
 
 proc oid*(sym: WireSymbol): Oid = sym.oid
 proc `ref`*(sym: WireSymbol): Ref = sym.ref
 
-proc grab*(mem: Membrane; key: Oid|Ref): WireSymbol =
+proc grab*(mem: Membrane; key: Oid): WireSymbol =
   ## Grab a `WireSymbol` from a `Membrane`.
-  result =
-    when key is Oid: mem.byOid.getOrDefault(key)
-    elif key is Ref: mem.byRef.getOrDefault(key)
-    else: {.error.}
-  if not result.isNil: inc result.count
+  mem.byOid.getOrDefault(key)
+
+proc grab*(mem: Membrane; key: Ref): WireSymbol =
+  ## Grab a `WireSymbol` from a `Membrane`.
+  mem.byRef.getOrDefault(key)
 
 proc drop*(mem: var Membrane; sym: WireSymbol) =
   ## Drop a `WireSymbol` from a `Membrane`.
-  assert sym.mem == mem, "cannot drop WireSymbol at the wrong Membrane"
-  assert sym.count > 0
   dec sym.count
   if sym.count < 1:
     mem.byOid.del sym.oid
@@ -46,4 +42,3 @@ proc newWireSymbol*(mem: var Membrane; o: Oid; r: Ref): WireSymbol =
   result = WireSymbol(oid: o, `ref`: r, count: 1)
   mem.byOid[result.oid] = result
   mem.byRef[result.`ref`] = result
-  when not defined(release): result.mem = mem