diff --git a/modules/ml/src/nbayes.cpp b/modules/ml/src/nbayes.cpp
index b9a966cd1d..5ad1b134d9 100644
--- a/modules/ml/src/nbayes.cpp
+++ b/modules/ml/src/nbayes.cpp
@@ -210,6 +210,8 @@ bool CvNormalBayesClassifier::train( const CvMat* _train_data, const CvMat* _res
                 prod_data[c2] += train_vec[c2]*val1;
         }
     }
+    cvReleaseMat( &responses );
+    responses = 0;
 
     /* calculate avg, covariance matrix, c */
     for( cls = 0; cls < nclasses; cls++ )