diff --git a/compiler/seminst.nim b/compiler/seminst.nim
index ed842d98ef..98f25efa7c 100644
--- a/compiler/seminst.nim
+++ b/compiler/seminst.nim
@@ -148,8 +148,8 @@ proc instGenericContainer(c: PContext, info: TLineInfo, header: PType): PType =
 proc instGenericContainer(c: PContext, n: PNode, header: PType): PType =
   result = instGenericContainer(c, n.info, header)
 
-proc fixupProcType(c: PContext, genericType: PType,
-                   inst: TInstantiation): PType =
+proc fixupProcTypeR(c: PContext, genericType: PType,
+                    inst: TInstantiation): PType =
   result = genericType
   if result == nil: return
 
@@ -167,53 +167,48 @@ proc fixupProcType(c: PContext, genericType: PType,
     if genericType.sons == nil: return
     var head = 0
     for i in 0 .. <genericType.sons.len:
-      var changed = fixupProcType(c, genericType.sons[i], inst)
+      let changed = fixupProcTypeR(c, genericType.sons[i], inst)
       if changed != genericType.sons[i]:
-        var changed = changed.skipIntLit
         if result == genericType:
           # the first detected change initializes the result
           result = copyType(genericType, genericType.owner, false)
           if genericType.n != nil:
             result.n = copyTree(genericType.n)
-
-        # XXX: doh, we have to treat seq and arrays as special case
-        # because sometimes the `@` magic will be applied to an empty
-        # sequence having the type tySequence(tyEmpty)
-        if changed.kind == tyEmpty and
-           genericType.kind notin {tyArray, tySequence}:
-          if genericType.kind == tyProc and i == 0:
-            # return types of procs are overwritten with nil
-            changed = nil
-          else:
-            # otherwise, `empty` is just erased from the signature
-            result.sons[i..i] = []
-            if result.n != nil: result.n.sons[i..i] = []
-            continue
-        
+        if changed.kind == tyEmpty:
+          result.sons[i..i] = []
+          if result.n != nil: result.n.sons[i..i] = []
+          continue
+        let changed = changed.skipIntLit
         result.sons[head] = changed
-        
         if result.n != nil:
           if result.n.kind == nkRecList:
             result.n.sons[head].typ = changed
           if result.n.kind == nkFormalParams:
-            if i != 0:
+            if i == 0:
+              nil
+            else:
               let origParam = result.n.sons[head].sym
               var param = copySym(origParam)
               param.typ = changed
               param.ast = origParam.ast
               result.n.sons[head] = newSymNode(param)
-
-      # won't be advanced on empty (void) nodes
       inc head
         
   of tyGenericInvokation:
     result = newTypeWithSons(c, tyGenericInvokation, genericType.sons)
     for i in 1 .. <genericType.sons.len:
-      result.sons[i] = fixupProcType(c, result.sons[i], inst)
+      result.sons[i] = fixupProcTypeR(c, result.sons[i], inst)
     result = instGenericContainer(c, getInfoContext(-1), result)
   else:
     nil
 
+proc fixupProcType(c: PContext, genericType: PType,
+                   inst: TInstantiation): PType =
+  result = copyType(genericType, genericType.owner, false)
+  result = fixupProcTypeR(c, result, inst)
+  for i in 0 .. <result.sons.len:
+    result.sons[i] = fixupProcTypeR(c, result.sons[i], inst)
+
 proc generateInstance(c: PContext, fn: PSym, pt: TIdTable,
                       info: TLineInfo): PSym =
   # no need to instantiate generic templates/macros:
@@ -243,7 +238,7 @@ proc generateInstance(c: PContext, fn: PSym, pt: TIdTable,
   var entry = TInstantiation.new
   entry.sym = result
   instantiateGenericParamList(c, n.sons[genericParamsPos], pt, entry[])
-  result.typ = fixupProcType(c, fn.typ, entry[])
+  result.typ = fixupProcTypeR(c, fn.typ, entry[])
   n.sons[genericParamsPos] = ast.emptyNode
   var oldPrc = GenericCacheGet(fn, entry[])
   if oldPrc == nil: