diff --git a/src/shared/type-predicates.ts b/src/shared/type-predicates.ts
index 59eb888..7f2a90a 100644
--- a/src/shared/type-predicates.ts
+++ b/src/shared/type-predicates.ts
@@ -12,4 +12,4 @@ export const isNumericString = (x: string): boolean => JSON.stringify(+x) === x;
 // A predicate for a valid identifier
 export type Identifier = string;
 export const isIdentifier = (x: any): x is Identifier =>
-    /[A-Za-z][A-Za-z0-9]*/i.test(x);
\ No newline at end of file
+    /^[A-Za-z][A-Za-z0-9]*/i.test(x);
\ No newline at end of file