diff --git a/src/rfc3986/abnf_regexp.py b/src/rfc3986/abnf_regexp.py
index 5852e4d..ba062b3 100644
--- a/src/rfc3986/abnf_regexp.py
+++ b/src/rfc3986/abnf_regexp.py
@@ -27,7 +27,7 @@
 ALPHA = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
 DIGIT = "0123456789"
 # https://tools.ietf.org/html/rfc3986#section-2.3
-UNRESERVED = UNRESERVED_CHARS = ALPHA + DIGIT + r"._!-"
+UNRESERVED = UNRESERVED_CHARS = ALPHA + DIGIT + r'._!-~'
 UNRESERVED_CHARS_SET = set(UNRESERVED_CHARS)
 NON_PCT_ENCODED_SET = RESERVED_CHARS_SET.union(UNRESERVED_CHARS_SET)
 # We need to escape the '-' in this case:
diff --git a/tests/test_normalizers.py b/tests/test_normalizers.py
index 1dbd6fa..eff650c 100644
--- a/tests/test_normalizers.py
+++ b/tests/test_normalizers.py
@@ -97,6 +97,7 @@ def test_fragment_normalization():
     ["component", "encoded_component"],
     [
         ("/%", "/%25"),
+        ("/~", "/~"),
         ("/%a", "/%25a"),
         ("/%ag", "/%25ag"),
         ("/%af", "/%af"),