diff --git a/src/any-map.ts b/src/any-map.ts
index 8791fde..c6909f1 100644
--- a/src/any-map.ts
+++ b/src/any-map.ts
@@ -32,7 +32,7 @@ export const AnyMap: AnyMap = function (map, mapUrl) {
     const no = sections[i + 1].offset;
     addSection(sections[i], mapUrl, mappings, sources, sourcesContent, names, no.line, no.column);
   }
-  for (; i < sections.length; i++) {
+  if (sections.length > 0) {
     addSection(sections[i], mapUrl, mappings, sources, sourcesContent, names, -1, -1);
   }
 
diff --git a/src/binary-search.ts b/src/binary-search.ts
index faf5fe6..d0f8845 100644
--- a/src/binary-search.ts
+++ b/src/binary-search.ts
@@ -97,6 +97,7 @@ export function memoizedBinarySearch(
   let high = haystack.length - 1;
   if (key === lastKey) {
     if (needle === lastNeedle) {
+      found = haystack[lastIndex][COLUMN] === needle;
       return lastIndex;
     }
 
diff --git a/test/binary-search.test.ts b/test/binary-search.test.ts
index eb4554b..309239f 100644
--- a/test/binary-search.test.ts
+++ b/test/binary-search.test.ts
@@ -1,4 +1,4 @@
-import { binarySearch } from '../src/binary-search';
+import { binarySearch, found, memoizedState, memoizedBinarySearch } from '../src/binary-search';
 import { test, describe } from './setup';
 
 type SourceMapSegment = [number];
@@ -376,3 +376,24 @@ describe('binary search', () => {
     });
   });
 });
+
+describe('memoizedBinarySearch', () => {
+  const array: SourceMapSegment[] = [[0], [5], [10]];
+
+  test('refinds same index', (t) => {
+    const memo = memoizedState();
+
+    t.is(memoizedBinarySearch(array, 6, memo, 0), 1);
+    t.is(memoizedBinarySearch(array, 6, memo, 0), 1);
+  });
+
+  test('restores found state', (t) => {
+    const memo = memoizedState();
+
+    t.is(memoizedBinarySearch(array, 6, memo, 0), 1);
+    binarySearch(array, 0, 0, array.length - 1);
+    t.is(found, true);
+    t.is(memoizedBinarySearch(array, 6, memo, 0), 1);
+    t.is(found, false);
+  });
+});