1 files changed, 1 insertions, 0 deletions
diff --git a/proc.c b/proc.c
index 83ec61d0f5..e0cba7109b 100644
--- a/proc.c
+++ b/proc.c
@@ -697,6 +697,7 @@ sym_proc_new(VALUE klass, VALUE sym)
     GetProcPtr(procval, proc);
 
     vm_block_type_set(&proc->block, block_type_symbol);
+    proc->is_lambda = TRUE;
     RB_OBJ_WRITE(procval, &proc->block.as.symbol, sym);
     return procval;
 }