diff --git a/src/converters/main.ts b/src/converters/main.ts
index 3d3ea7f..39bac4a 100644
--- a/src/converters/main.ts
+++ b/src/converters/main.ts
@@ -163,7 +163,7 @@ export const getPossibleConversions = (
   return possibleConversions[fromClean] || {};
 };
 
-const allTargets: { [key: string]: string[] | undefined } = {};
+const allTargets: { [key: string]: string[]} = {};
 
 for (const converterName in properties) {
   const converterProperties = properties[converterName]?.properties;