diff --git a/TensionUniverse/BlackHole/Q131_tension_free_energy.md b/TensionUniverse/BlackHole/Q131_tension_free_energy.md
index 1cb08fcd..f5668fb3 100644
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@@ -1,4 +1,4 @@
-<!-- QUESTION_ID: TU-Q131-->
+<!-- QUESTION_ID: TU-Q131 -->
 # Q131 · Tension mediated free energy in open physical systems
 
 ## 0. Header metadata