diff --git a/packages/shared/src/uri.test.ts b/packages/shared/src/uri.test.ts
index 34fef348..eb41ca05 100644
--- a/packages/shared/src/uri.test.ts
+++ b/packages/shared/src/uri.test.ts
@@ -17,6 +17,9 @@ describe('safeEncodeURIComponent', () => {
     expect(safeEncodeURIComponent('\uDC00\uD800')).toBe('%EF%BF%BD%EF%BF%BD')
     // a well-formed pair next to a lone surrogate is kept intact
     expect(safeEncodeURIComponent('😀\uD83D')).toBe('%F0%9F%98%80%EF%BF%BD')
+    expect(safeEncodeURIComponent('\u{1F600}\uDE00')).toBe('%F0%9F%98%80%EF%BF%BD')
+    expect(safeEncodeURIComponent('\u{10FFFF}\uD800')).toBe('%F4%8F%BF%BF%EF%BF%BD')
+    expect(safeEncodeURIComponent('\uD800\u{10000}\uDFFF')).toBe('%EF%BF%BD%F0%90%80%80%EF%BF%BD')
   })
 })
 
diff --git a/packages/shared/src/uri.ts b/packages/shared/src/uri.ts
index 7804be01..d16700d2 100644
--- a/packages/shared/src/uri.ts
+++ b/packages/shared/src/uri.ts
@@ -1,5 +1,5 @@
-const LONE_SURROGATE_REGEX =
-  /[\uD800-\uDBFF](?![\uDC00-\uDFFF])|(?<![\uD800-\uDBFF])[\uDC00-\uDFFF]/g
+// with the u flag a well-formed surrogate pair is one code point, so only lone surrogates match
+const LONE_SURROGATE_REGEX = /[\uD800-\uDFFF]/gu
 const PERCENT_ESCAPES_REGEX = /(?:%[0-9A-F]{2})+/gi
 
 /**