diff --git a/packages/pg-connection-string/index.js b/packages/pg-connection-string/index.js
index 139cc17b1..2c0cf646f 100644
--- a/packages/pg-connection-string/index.js
+++ b/packages/pg-connection-string/index.js
@@ -18,8 +18,9 @@ function parse(str, options = {}) {
   let result
   let dummyHost = false
   if (/ |%[^a-f0-9]|%[a-f0-9][^a-f0-9]/i.test(str)) {
-    // Ensure spaces are encoded as %20
-    str = encodeURI(str).replace(/%25(\d\d)/g, '%$1')
+    // Ensure spaces are encoded as %20, and undo the double encoding of
+    // existing percent-escapes (e.g. %2F, %3a) that encodeURI also produces
+    str = encodeURI(str).replace(/%25([0-9a-f]{2})/gi, '%$1')
   }
 
   try {
diff --git a/packages/pg-connection-string/test/parse.ts b/packages/pg-connection-string/test/parse.ts
index 562c3ece0..9cf22e682 100644
--- a/packages/pg-connection-string/test/parse.ts
+++ b/packages/pg-connection-string/test/parse.ts
@@ -125,6 +125,18 @@ describe('parse', function () {
     subject.database?.should.equal(' u%20rl')
   })
 
+  it('keeps percent-encoded characters when the url also contains a space', function () {
+    const subject = parse('postgres://app:s3cr%2Ft%3A@localhost/db?options=-c search_path=app')
+    subject.password?.should.equal('s3cr/t:')
+    subject.options?.should.equal('-c search_path=app')
+  })
+
+  it('keeps lowercase percent-encoded characters when the url also contains a stray percent sign', function () {
+    const subject = parse('postgres://app:s3cr%2bt@localhost/50%off')
+    subject.password?.should.equal('s3cr+t')
+    subject.database?.should.equal('50%off')
+  })
+
   it('relative url sets database', function () {
     const relative = 'different_db_on_default_host'
     const subject = parse(relative)