diff --git a/bytecode_graph/render.py b/bytecode_graph/render.py
index 0f7cc44..0b8c02f 100644
--- a/bytecode_graph/render.py
+++ b/bytecode_graph/render.py
@@ -47,7 +47,8 @@ def get_blocks(self):
             blocks.append((prev, x))
             prev = None
 
-        blocks.append((prev, x))
+        if prev is not None:
+            blocks.append((prev, x))
         return blocks
 
     def get_edges(self, blocks):