diff --git a/cpp/core/src/qrcode/detector/Detector.cpp b/cpp/core/src/qrcode/detector/Detector.cpp
index bbe77b419..7ed6b3a5a 100644
--- a/cpp/core/src/qrcode/detector/Detector.cpp
+++ b/cpp/core/src/qrcode/detector/Detector.cpp
@@ -40,7 +40,7 @@ namespace qrcode {
     image_(image) { }
     
     Ref<DetectorResult> Detector::detect() {
-      if (!BlackPointEstimationMethod_2D == image_->getLastEstimationMethod()) {
+      if (BlackPointEstimationMethod_2D != image_->getLastEstimationMethod()) {
         image_->estimateBlackPoint(BlackPointEstimationMethod_2D, 0);
       }