diff --git a/modules/core/src/matmul.cpp b/modules/core/src/matmul.cpp
index 4be9c4daa3..06d57685fb 100644
--- a/modules/core/src/matmul.cpp
+++ b/modules/core/src/matmul.cpp
@@ -2994,6 +2994,7 @@ PCA& PCA::computeVar(InputArray _data, InputArray __mean, int flags, double reta
     {
         CV_Assert( _mean.size() == mean_sz );
         _mean.convertTo(mean, ctype);
+        covar_flags |= CV_COVAR_USE_AVG;
     }
 
     calcCovarMatrix( data, covar, mean, covar_flags, ctype );