diff --git a/text/problem/theotherthing/solution.tex b/text/problem/theotherthing/solution.tex
index 54b7e49..bc970db 100644
--- a/text/problem/theotherthing/solution.tex
+++ b/text/problem/theotherthing/solution.tex
@@ -114,7 +114,7 @@ At each step it selects a new timestamp that corresponds to a regular ({non-\the
     }
 
     % Save new point to landmarks
-    $L'.add(\optimi)$\;
+    $L'$.add(\optimi)\;
 
     % Add new option
     \optim.append($L' \setminus L$)\;