diff --git a/index.d.ts b/index.d.ts
index df58914f..d9c6e10e 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -50,7 +50,7 @@ declare type Twemoji = {
   base: string;
   ext: string;
   className: string;
-  size: string | number;
+  size: string;
   convert: {
     /**
      * Given an HEX codepoint, returns UTF16 surrogate pairs.