diff --git a/lib/v8-to-istanbul.js b/lib/v8-to-istanbul.js
index e5be920c..f4bd25d0 100644
--- a/lib/v8-to-istanbul.js
+++ b/lib/v8-to-istanbul.js
@@ -257,7 +257,8 @@ module.exports = class V8ToIstanbul {
     }
     this.branches[path] = this.branches[path] || []
     this.branches[path].forEach((branch, index) => {
-      const ignore = source.lines[branch.startLine - 1].ignore
+      const srcLine = source.lines[branch.startLine - 1]
+      const ignore = srcLine === undefined ? true : srcLine.ignore
       branches.branchMap[`${index}`] = branch.toIstanbul()
       branches.b[`${index}`] = [ignore ? 1 : branch.count]
     })
@@ -271,7 +272,8 @@ module.exports = class V8ToIstanbul {
     }
     this.functions[path] = this.functions[path] || []
     this.functions[path].forEach((fn, index) => {
-      const ignore = source.lines[fn.startLine - 1].ignore
+      const srcLine = source.lines[fn.startLine - 1]
+      const ignore = srcLine === undefined ? true : srcLine.ignore
       functions.fnMap[`${index}`] = fn.toIstanbul()
       functions.f[`${index}`] = ignore ? 1 : fn.count
     })