diff --git a/frontend/src/utils/index.ts b/frontend/src/utils/index.ts
index 8ba54d2dc207529325a2c142ac1f9c73aea00e14..b525f6547c0d4e40cda743e6937e72f19d816250 100644
--- a/frontend/src/utils/index.ts
+++ b/frontend/src/utils/index.ts
@@ -205,6 +205,7 @@ function stringContainsIllegalChars(string: string): boolean {
   // ----- Basic Latin -----
   // U+0020 (Space)
   // U+002D (Hyphen-minus)
+  // U+002E (Full stop)
   // U+0041 - U+005A (Latin Alphabet: Uppercase)
   // U+0061 - U+007A (Latin Alphabet: Lowercase)
   // ----- Latin-1 Supplement -----
@@ -216,7 +217,7 @@ function stringContainsIllegalChars(string: string): boolean {
   // U+0100 - U+017F (European Latin)
 
   // eslint-disable-next-line no-control-regex
-  return /[^\u0020\u002D\u0041-\u005A\u0061-\u007A\u00C0-\u00D6\u00D8-\u00F6\u00F8-\u017F]/g.test(
+  return /[^\u0020\u002D\u002E\u0041-\u005A\u0061-\u007A\u00C0-\u00D6\u00D8-\u00F6\u00F8-\u017F]/g.test(
     string
   )
 }
diff --git a/greg/tests/test_utils.py b/greg/tests/test_utils.py
index 336285ebfc8a91fae60600d7b4da25793ef46d64..056d3335fc9ac034c52978659ef9d506cf8b15e1 100644
--- a/greg/tests/test_utils.py
+++ b/greg/tests/test_utils.py
@@ -34,6 +34,7 @@ def test_not_valid_so_number():
     [
         ("AZ az ÀÖ ØÞßö øÿ Āſ", False),
         ("Kari-Mette", False),
+        ("Kari M.", False),
         ("aaƂåå", True),
         ("!", True),
         ("÷", True),
diff --git a/greg/utils.py b/greg/utils.py
index 63e17472a7a7b5fa6cb4af6f9dbc4d4e1ff96ef8..ad3123196876cc52cbe7670bca2ad530ca272c4a 100644
--- a/greg/utils.py
+++ b/greg/utils.py
@@ -227,6 +227,7 @@ def string_contains_illegal_chars(string: str) -> bool:
     # ----- Basic Latin -----
     # U+0020 (Space)
     # U+002D (Hyphen-minus)
+    # U+002E (Full stop)
     # U+0041 - U+005A (Latin Alphabet: Uppercase)
     # U+0061 - U+007A (Latin Alphabet: Lowercase)
     # ----- Latin-1 Supplement -----
@@ -238,7 +239,7 @@ def string_contains_illegal_chars(string: str) -> bool:
     # U+0100 - U+017F (European Latin)
     return bool(
         re.search(
-            r"[^\u0020\u002D\u0041-\u005A\u0061-\u007A\u00C0-\u00D6\u00D8-\u00F6\u00F8-\u017F]",
+            r"[^\u0020\u002D\u002E\u0041-\u005A\u0061-\u007A\u00C0-\u00D6\u00D8-\u00F6\u00F8-\u017F]",
             string,
         )
     )