diff --git a/src/browser/renderer/dom/DomRendererRowFactory.test.ts b/src/browser/renderer/dom/DomRendererRowFactory.test.ts
index 026d8881..fdbcea33 100644
--- a/src/browser/renderer/dom/DomRendererRowFactory.test.ts
+++ b/src/browser/renderer/dom/DomRendererRowFactory.test.ts
@@ -138,7 +138,7 @@ describe('DomRendererRowFactory', () => {
           lineData.setCell(0, cell);
           const fragment = rowFactory.createRow(lineData, 0, false, undefined, 0, false, 5, 20);
           assert.equal(getFragmentHtml(fragment),
-            '<span class="xterm-underline-1">a</span>'
+            '<span class="xterm-underline-1" style="text-decoration-color: rgb(255,255,255);">a</span>'
           );
         });
         it('should add class for double underline style', () => {
@@ -149,7 +149,7 @@ describe('DomRendererRowFactory', () => {
           lineData.setCell(0, cell);
           const fragment = rowFactory.createRow(lineData, 0, false, undefined, 0, false, 5, 20);
           assert.equal(getFragmentHtml(fragment),
-            '<span class="xterm-underline-2">a</span>'
+            '<span class="xterm-underline-2" style="text-decoration-color: rgb(255,255,255);">a</span>'
           );
         });
         it('should add class for curly underline style', () => {
@@ -160,7 +160,7 @@ describe('DomRendererRowFactory', () => {
           lineData.setCell(0, cell);
           const fragment = rowFactory.createRow(lineData, 0, false, undefined, 0, false, 5, 20);
           assert.equal(getFragmentHtml(fragment),
-            '<span class="xterm-underline-3">a</span>'
+            '<span class="xterm-underline-3" style="text-decoration-color: rgb(255,255,255);">a</span>'
           );
         });
         it('should add class for double dotted style', () => {
@@ -171,7 +171,7 @@ describe('DomRendererRowFactory', () => {
           lineData.setCell(0, cell);
           const fragment = rowFactory.createRow(lineData, 0, false, undefined, 0, false, 5, 20);
           assert.equal(getFragmentHtml(fragment),
-            '<span class="xterm-underline-4">a</span>'
+            '<span class="xterm-underline-4" style="text-decoration-color: rgb(255,255,255);">a</span>'
           );
         });
         it('should add class for dashed underline style', () => {
@@ -182,7 +182,7 @@ describe('DomRendererRowFactory', () => {
           lineData.setCell(0, cell);
           const fragment = rowFactory.createRow(lineData, 0, false, undefined, 0, false, 5, 20);
           assert.equal(getFragmentHtml(fragment),
-            '<span class="xterm-underline-5">a</span>'
+            '<span class="xterm-underline-5" style="text-decoration-color: rgb(255,255,255);">a</span>'
           );
         });
       });
diff --git a/src/common/buffer/BufferLine.test.ts b/src/common/buffer/BufferLine.test.ts
index fa15a854..111aae03 100644
--- a/src/common/buffer/BufferLine.test.ts
+++ b/src/common/buffer/BufferLine.test.ts
@@ -45,7 +45,7 @@ describe('AttributeData', () => {
       assert.equal(attrs.getUnderlineColor(), 45);
 
       // should use FG color if underlineColor holds no value
-      attrs.extended.underlineColor = -1;
+      attrs.extended.underlineColor = 0;
       attrs.fg |= Attributes.CM_P256 | 123;
       assert.equal(attrs.getUnderlineColor(), 123);
     });
@@ -62,7 +62,7 @@ describe('AttributeData', () => {
       assert.equal(attrs.getUnderlineColor(), (1 << 16) | (2 << 8) | 3);
 
       // should use FG color if underlineColor holds no value
-      attrs.extended.underlineColor = -1;
+      attrs.extended.underlineColor = 0;
       attrs.fg |= Attributes.CM_P256 | 123;
       assert.equal(attrs.getUnderlineColor(), 123);
     });