diff --git a/compiler/semexprs.nim b/compiler/semexprs.nim
index d3650f984..34e8c6fcd 100644
--- a/compiler/semexprs.nim
+++ b/compiler/semexprs.nim
@@ -1629,8 +1629,9 @@ proc instantiateCreateFlowVarCall(c: PContext; t: PType;
   result = c.semGenerateInstance(c, sym, bindings, info)
   # since it's an instantiation, we unmark it as a compilerproc. Otherwise
   # codegen would fail:
-  result.flags = result.flags - {sfCompilerProc, sfExportC, sfImportC}
-  result.loc.r = nil
+  if sfCompilerProc in result.flags:
+    result.flags = result.flags - {sfCompilerProc, sfExportC, sfImportC}
+    result.loc.r = nil
 
 proc setMs(n: PNode, s: PSym): PNode = 
   result = n