diff --git a/modules/objdetect/src/aruco/aruco_detector.cpp b/modules/objdetect/src/aruco/aruco_detector.cpp
index a128710f4d..0075d3e5a8 100644
--- a/modules/objdetect/src/aruco/aruco_detector.cpp
+++ b/modules/objdetect/src/aruco/aruco_detector.cpp
@@ -755,7 +755,7 @@ struct ArucoDetector::ArucoDetectorImpl {
                 performCornerSubpixRefinement(grey, grey_pyramid, closest_pyr_image_idx, candidates, dictionary);
             }
         } else if (DictionaryMode::Multi == dictMode) {
-            map<size_t, vector<MarkerCandidateTree>> candidatesPerDictionarySize;
+            map<int, vector<MarkerCandidateTree>> candidatesPerDictionarySize;
             for (const Dictionary& dictionary : dictionaries) {
                 candidatesPerDictionarySize.emplace(dictionary.markerSize, vector<MarkerCandidateTree>());
             }