--- a/devtools/client/debugger/src/components/Editor/DebugLine.js
+++ b/devtools/client/debugger/src/components/Editor/DebugLine.js
@@ -66,26 +66,30 @@ export class DebugLine extends PureCompo
   setDebugLine(why: Why, frame: Frame, source: ?SourceWithContent) {
     if (!isDocumentReady(source, frame)) {
       return;
     }
     const sourceId = frame.location.sourceId;
     const doc = getDocument(sourceId);
 
     let { line, column } = toEditorPosition(frame.location);
-    const { markTextClass, lineClass } = this.getTextClasses(why);
+    let { markTextClass, lineClass } = this.getTextClasses(why);
     doc.addLineClass(line, "line", lineClass);
 
     const lineText = doc.getLine(line);
     column = Math.max(column, getIndentation(lineText));
 
     // If component updates because user clicks on
     // another source tab, codeMirror will be null.
     const columnEnd = doc.cm ? getTokenEnd(doc.cm, line, column) : null;
 
+    if (columnEnd === null) {
+      markTextClass += " to-line-end";
+    }
+
     this.debugExpression = doc.markText(
       { ch: column, line },
       { ch: columnEnd, line },
       { className: markTextClass }
     );
   }
 
   clearDebugLine(why: Why, frame: Frame, source: ?SourceWithContent) {

--- a/devtools/client/debugger/src/components/Editor/Editor.css
+++ b/devtools/client/debugger/src/components/Editor/Editor.css
@@ -104,16 +104,20 @@ html[dir="rtl"] .editor-mount {
 .theme-dark .editor-wrapper .CodeMirror-line .cm-comment {
   color: var(--theme-comment);
 }
 
 .debug-expression {
   background-color: var(--debug-expression-background);
 }
 
+.to-line-end ~ .CodeMirror-widget {
+  background-color: var(--debug-expression-background);
+}
+
 .debug-expression-error {
   background-color: var(--debug-expression-error-background);
 }
 
 :not(.conditional-breakpoint-panel) .new-debug-line .CodeMirror-line {
   background-color: transparent !important;
   outline: var(--debug-line-border) solid 1px;
 }

--- a/devtools/client/debugger/src/components/Editor/tests/DebugLine.spec.js
+++ b/devtools/client/debugger/src/components/Editor/tests/DebugLine.spec.js
@@ -121,22 +121,22 @@ describe("DebugLine Component", () => {
           [toEditorLine("foo", firstLine), "line", "new-debug-line"],
           [toEditorLine("foo", secondLine), "line", "new-debug-line"],
         ]);
 
         expect(doc.markText.mock.calls).toEqual([
           [
             { ch: 2, line: toEditorLine("foo", firstLine) },
             { ch: null, line: toEditorLine("foo", firstLine) },
-            { className: "debug-expression" },
+            { className: "debug-expression to-line-end" },
           ],
           [
             { ch: 2, line: toEditorLine("foo", secondLine) },
             { ch: null, line: toEditorLine("foo", secondLine) },
-            { className: "debug-expression" },
+            { className: "debug-expression to-line-end" },
           ],
         ]);
 
         expect(clear.mock.calls).toEqual([[]]);
       });
     });
 
     describe("when there is no selected frame", () => {

--- a/devtools/client/debugger/src/utils/editor/index.js
+++ b/devtools/client/debugger/src/utils/editor/index.js
@@ -260,11 +260,12 @@ export function getCursorLine(codeMirror
   return codeMirror.getCursor().line;
 }
 
 export function getTokenEnd(codeMirror: Object, line: number, column: number) {
   const token = codeMirror.getTokenAt({
     line: line,
     ch: column + 1,
   });
+  const tokenString = token.string;
 
-  return token.end;
+  return tokenString === "{" || tokenString === "[" ? null : token.end;
 }