diff --git a/src/syntax/all-math-operators-by-glyph.ts b/src/syntax/all-math-operators-by-glyph.ts
index 5ec0651..8ba1576 100644
--- a/src/syntax/all-math-operators-by-glyph.ts
+++ b/src/syntax/all-math-operators-by-glyph.ts
@@ -50,7 +50,6 @@ export const allMathOperatorsByGlyph: Record<string, string> = {
   '--': '--',
   '++': '++',
   '&': '\\&',
-  undefined: '',
   '∜': '\\sqrt[4]{}',
   '∛': '\\sqrt[3]{}',
   '√': '\\sqrt{}',