diff --git a/extensions/debug-server-ready/src/extension.ts b/extensions/debug-server-ready/src/extension.ts
index b3525281111..22a8ff836d3 100644
--- a/extensions/debug-server-ready/src/extension.ts
+++ b/extensions/debug-server-ready/src/extension.ts
@@ -22,8 +22,8 @@ interface ServerReadyAction {
 	killOnServerStop?: boolean;
 }
 
-// Escape codes, compiled from https://invisible-island.net/xterm/ctlseqs/ctlseqs.html#h3-Functions-using-CSI-_-ordered-by-the-final-character_s_
-const CSI_SEQUENCE = /(:?\x1b\[|\x9B)[=?>!]?[\d;:]*["$#'* ]?[a-zA-Z@^`{}|~]/g;
+// From src/vs/base/common/strings.ts
+const CSI_SEQUENCE = /(?:(?:\x1b\[|\x9B)[=?>!]?[\d;:]*["$#'* ]?[a-zA-Z@^`{}|~])|(:?\x1b\].*?\x07)/g;
 
 /**
  * Froms vs/base/common/strings.ts in core
diff --git a/src/vs/base/common/strings.ts b/src/vs/base/common/strings.ts
index 2636d667674..79d22ee0e6d 100644
--- a/src/vs/base/common/strings.ts
+++ b/src/vs/base/common/strings.ts
@@ -766,7 +766,7 @@ export function lcut(text: string, n: number, prefix = '') {
 
 // Escape codes, compiled from https://invisible-island.net/xterm/ctlseqs/ctlseqs.html#h3-Functions-using-CSI-_-ordered-by-the-final-character_s_
 // Plus additional markers for custom `\x1b]...\x07` instructions.
-const CSI_SEQUENCE = /(:?(:?\x1b\[|\x9B)[=?>!]?[\d;:]*["$#'* ]?[a-zA-Z@^`{}|~])|(:?\x1b\].*?\x07)/g;
+const CSI_SEQUENCE = /(?:(?:\x1b\[|\x9B)[=?>!]?[\d;:]*["$#'* ]?[a-zA-Z@^`{}|~])|(:?\x1b\].*?\x07)/g;
 
 /** Iterates over parts of a string with CSI sequences */
 export function* forAnsiStringParts(str: string) {
diff --git a/src/vs/base/test/common/strings.test.ts b/src/vs/base/test/common/strings.test.ts
index c75f9e992d7..bb9e5db1d51 100644
--- a/src/vs/base/test/common/strings.test.ts
+++ b/src/vs/base/test/common/strings.test.ts
@@ -536,6 +536,11 @@ suite('Strings', () => {
 				`expect to forAnsiStringParts ${JSON.stringify(sequence)}`
 			);
 		}
+
+		// #209937
+		assert.strictEqual(
+			strings.removeAnsiEscapeCodes(`localhost:\x1b[31m1234`),
+			'localhost:1234',);
 	});
 
 	test('removeAnsiEscapeCodesFromPrompt', () => {