diff --git a/AGENTS.md b/AGENTS.md
index 0b846ab..ee5a94c 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -78,7 +78,7 @@ ItaxCode.decode(tax_code) #=> Hash:
 #   code:       String,          # the input code, upcased
 #   gender:     "M" | "F",
 #   birthdate:  String,          # "YYYY-MM-DD"
-#   birthplace: {                # nil if not found in either CSV
+#   birthplace: {                # raises InvalidTaxCodeError if not found in either CSV
 #     code:       String,        # e.g. "F205"
 #     province:   String,        # e.g. "MI"
 #     name:       String,        # e.g. "MILANO"
diff --git a/lib/itax_code/parser.rb b/lib/itax_code/parser.rb
index 97c1ee0..e110025 100644
--- a/lib/itax_code/parser.rb
+++ b/lib/itax_code/parser.rb
@@ -92,10 +92,12 @@ def birthplace(src = utils.cities, stop: false)
         place = src.find { |item| item["code"] == birthplace_code && in_dates?(item) }
 
         if place.nil?
-          birthplace(utils.countries, stop: true) unless stop
-        else
-          place.to_h.transform_keys(&:to_sym)
+          return birthplace(utils.countries, stop: true) unless stop
+
+          raise InvalidTaxCodeError
         end
+
+        place.to_h.transform_keys(&:to_sym)
       end
 
       def birthplace_code
diff --git a/test/itax_code/parser_test.rb b/test/itax_code/parser_test.rb
index ba12176..b0d0d17 100644
--- a/test/itax_code/parser_test.rb
+++ b/test/itax_code/parser_test.rb
@@ -29,9 +29,8 @@ class ParserTest < Minitest::Test
       end
     end
 
-    # FIXME: This behaviour needs to be fixed, maybe by raising an InvalidTaxCodeError.
-    test "returns nil birthplace when the lookup on both cities and countries fails" do
-      assert_nil klass.new("BRRDRN70M41ZXXXE").decode[:birthplace]
+    test "raises InvalidTaxCodeError when birthplace code is not found in cities or countries" do
+      assert_raises(klass::InvalidTaxCodeError) { klass.new("BRRDRN70M41ZXXXE").decode }
     end
 
     test "raises NoTaxCodeError with an empty tax code" do