diff --git a/CHANGES.md b/CHANGES.md
index cee783ed..51b91522 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -2,6 +2,7 @@
 
 ## python-markdown2 2.5.6 (not yet released)
 
+- [pull #749] URL-encode destinations generated by the `link-patterns` extra (#55)
 - [pull #746] Preserve query strings and fragments in `markdown-file-links` conversions, including reference-link targets.
 - [pull #739] Fix `header-ids` extra putting sanitized HTML into header ids in safe mode, which allowed attribute injection (#649)
 - [pull #732] Fix excessive CPU use in the inline HTML tokenizer on repeated unclosed tag fragments (#707)
diff --git a/lib/markdown2.py b/lib/markdown2.py
index 3632a54e..a0a8fbef 100755
--- a/lib/markdown2.py
+++ b/lib/markdown2.py
@@ -133,6 +133,7 @@
 from collections.abc import Collection
 from enum import IntEnum, auto
 from os import urandom
+from urllib.parse import quote
 
 # ---- type defs
 _safe_mode = Literal['replace', 'escape']
@@ -3903,7 +3904,7 @@ def run(self, text: str):
                     continue
 
                 escaped_href = (
-                    href.replace('"', '"')  # b/c of attr quote
+                    quote(href, safe=":/?#[]@!$&'()*+,;=%")
                         # To avoid markdown <em> and <strong>:
                         .replace('*', self.md._escape_table['*'])
                         .replace('_', self.md._escape_table['_']))
diff --git a/test/tm-cases/link_patterns_url_encoding.html b/test/tm-cases/link_patterns_url_encoding.html
new file mode 100644
index 00000000..e571a7b4
--- /dev/null
+++ b/test/tm-cases/link_patterns_url_encoding.html
@@ -0,0 +1 @@
+<p><a href="lorem%20foo%20bar%20ipsum">foo bar</a></p>
diff --git a/test/tm-cases/link_patterns_url_encoding.opts b/test/tm-cases/link_patterns_url_encoding.opts
new file mode 100644
index 00000000..f95094df
--- /dev/null
+++ b/test/tm-cases/link_patterns_url_encoding.opts
@@ -0,0 +1,5 @@
+{"extras": ["link-patterns"],
+ "link_patterns": [
+    (re.compile(r"^(.*)$"), r"lorem \1 ipsum"),
+ ],
+}
diff --git a/test/tm-cases/link_patterns_url_encoding.text b/test/tm-cases/link_patterns_url_encoding.text
new file mode 100644
index 00000000..d675fa44
--- /dev/null
+++ b/test/tm-cases/link_patterns_url_encoding.text
@@ -0,0 +1 @@
+foo bar