diff --git a/src/lib/forms-shared.ts b/src/lib/forms-shared.ts
index 930bd46..f123154 100644
--- a/src/lib/forms-shared.ts
+++ b/src/lib/forms-shared.ts
@@ -151,11 +151,18 @@ export function applyCase(value: string, modifier?: string | null): string {
       return value.toLowerCase().replace(/\b([a-z\u00C0-\u024F])/g, (c) => c.toUpperCase());
     case "sentence":
     case "capitalize": {
-      // Lowercase the whole string, then capitalize the first letter of each sentence.
+      // Lowercase, then uppercase the first letter and the first letter
+      // following any sentence terminator. Skips leading non-letters
+      // (numbers, punctuation, whitespace) so "123 main st" -> "123 Main st"
+      // is unchanged but "main st." -> "Main st." works.
       const lower = value.toLowerCase();
-      return lower.replace(/(^\s*[a-z\u00C0-\u024F])|([.!?]\s+[a-z\u00C0-\u024F])/g, (s) =>
-        s.toUpperCase(),
+      // First letter anywhere at the start of the string (after non-letters).
+      let result = lower.replace(/^[^a-z\u00C0-\u024F]*[a-z\u00C0-\u024F]/, (s) =>
+        s.slice(0, -1) + s.slice(-1).toUpperCase(),
       );
+      // First letter after each sentence terminator.
+      result = result.replace(/([.!?]\s+)([a-z\u00C0-\u024F])/g, (_m, p, c) => p + c.toUpperCase());
+      return result;
     }
     default:
       return value;