diff --git a/modules/flann/include/opencv2/flann/dist.h b/modules/flann/include/opencv2/flann/dist.h
index 07a1cc29c6..b092b531a1 100644
--- a/modules/flann/include/opencv2/flann/dist.h
+++ b/modules/flann/include/opencv2/flann/dist.h
@@ -708,7 +708,7 @@ struct KL_Divergence
         Iterator1 last = a + size;
 
         while (a < last) {
-            if (* b != 0) {
+            if ( *a != 0 && *b != 0 ) {
                 ResultType ratio = (ResultType)(*a / *b);
                 if (ratio>0) {
                     result += *a * log(ratio);
@@ -731,7 +731,7 @@ struct KL_Divergence
     inline ResultType accum_dist(const U& a, const V& b, int) const
     {
         ResultType result = ResultType();
-        if( *b != 0 ) {
+        if( a != 0 && b != 0 ) {
             ResultType ratio = (ResultType)(a / b);
             if (ratio>0) {
                 result = a * log(ratio);
diff --git a/modules/flann/include/opencv2/flann/kmeans_index.h b/modules/flann/include/opencv2/flann/kmeans_index.h
index 7574e7faf8..f743d75224 100644
--- a/modules/flann/include/opencv2/flann/kmeans_index.h
+++ b/modules/flann/include/opencv2/flann/kmeans_index.h
@@ -650,7 +650,8 @@ private:
      *
      * Params:
      *     node = the node to use
-     *     indices = the indices of the points belonging to the node
+     *     indices = array of indices of the points belonging to the node
+     *     indices_length = number of indices in the array
      */
     void computeNodeStatistics(KMeansNodePtr node, int* indices, int indices_length)
     {
@@ -662,7 +663,7 @@ private:
 
         memset(mean,0,veclen_*sizeof(DistanceType));
 
-        for (size_t i=0; i<size_; ++i) {
+        for (size_t i=0; i<(size_t)indices_length; ++i) {
             ElementType* vec = dataset_[indices[i]];
             for (size_t j=0; j<veclen_; ++j) {
                 mean[j] += vec[j];
diff --git a/modules/flann/include/opencv2/flann/lsh_index.h b/modules/flann/include/opencv2/flann/lsh_index.h
index ee620dae3e..cf37bc1c6f 100644
--- a/modules/flann/include/opencv2/flann/lsh_index.h
+++ b/modules/flann/include/opencv2/flann/lsh_index.h
@@ -71,9 +71,9 @@ struct LshIndexParams : public IndexParams
 };
 
 /**
- * Randomized kd-tree index
+ * Locality-sensitive hashing  index
  *
- * Contains the k-d trees and other information for indexing a set of points
+ * Contains the tables and other information for indexing a set of points
  * for nearest-neighbor matching.
  */
 template<typename Distance>
diff --git a/modules/flann/include/opencv2/flann/lsh_table.h b/modules/flann/include/opencv2/flann/lsh_table.h
index db8b5af946..8f5250171b 100644
--- a/modules/flann/include/opencv2/flann/lsh_table.h
+++ b/modules/flann/include/opencv2/flann/lsh_table.h
@@ -245,7 +245,7 @@ public:
     {
         std::cerr << "LSH is not implemented for that type" << std::endl;
         assert(0);
-        return 1;
+        return 0;
     }
 
     /** Get statistics about the table
diff --git a/modules/flann/include/opencv2/flann/result_set.h b/modules/flann/include/opencv2/flann/result_set.h
index 735028fb45..02f827ada0 100644
--- a/modules/flann/include/opencv2/flann/result_set.h
+++ b/modules/flann/include/opencv2/flann/result_set.h
@@ -196,12 +196,10 @@ public:
 #endif
             {
                 // Check for duplicate indices
-                int j = i - 1;
-                while ((j >= 0) && (dists[j] == dist)) {
+                for (int j = i; dists[j] == dist && j--;) {
                     if (indices[j] == index) {
                         return;
                     }
-                    --j;
                 }
                 break;
             }