diff --git a/frontend/learn.c b/frontend/learn.c
index 94b4d6a6..6d6cd4f5 100644
--- a/frontend/learn.c
+++ b/frontend/learn.c
@@ -95,7 +95,10 @@ static void learn_option_finish(learn_option_t* opt)
 {
     int i;
 
+    free(opt->logbase);
     free(opt->model);
+    free(opt->algorithm);
+    free(opt->type);
 
     for (i = 0;i < opt->num_params;++i) {
         free(opt->params[i]);
diff --git a/frontend/reader.c b/frontend/reader.c
index a8f58f5c..b9f0ecf7 100644
--- a/frontend/reader.c
+++ b/frontend/reader.c
@@ -116,6 +116,7 @@ int read_data(FILE *fpi, FILE *fpo, crfsuite_data_t* data, int group)
                         /* Unrecognized declaration. */
                         fprintf(fpo, "\n");
                         fprintf(fpo, "ERROR: unrecognized declaration: %s\n", token->attr);
+                        iwa_delete(iwa);
                         return -1;
                     }
                 } else {
@@ -148,5 +149,7 @@ int read_data(FILE *fpi, FILE *fpo, crfsuite_data_t* data, int group)
     progress(fpo, prev, 100);
     fprintf(fpo, "\n");
 
+    iwa_delete(iwa);
+
     return n;
 }
diff --git a/lib/cqdb/src/cqdb.c b/lib/cqdb/src/cqdb.c
index f164a38f..9500e93f 100644
--- a/lib/cqdb/src/cqdb.c
+++ b/lib/cqdb/src/cqdb.c
@@ -268,6 +268,7 @@ int cqdb_writer_close(cqdb_writer_t* dbw)
 
     /* Initialize the file header. */
     strncpy((char*)header.chunkid, CHUNKID, 4);
+    header.flag = 0;
     header.byteorder = BYTEORDER_CHECK;
     header.bwd_offset = 0;
     header.bwd_size = dbw->bwd_num;
diff --git a/lib/crf/src/crf1d_encode.c b/lib/crf/src/crf1d_encode.c
index 4dd32e08..598c8b43 100644
--- a/lib/crf/src/crf1d_encode.c
+++ b/lib/crf/src/crf1d_encode.c
@@ -98,6 +98,8 @@ static void crf1de_init(crf1de_t *crf1de)
 
 static void crf1de_finish(crf1de_t *crf1de)
 {
+    int i;
+
     if (crf1de->ctx != NULL) {
         crf1dc_delete(crf1de->ctx);
         crf1de->ctx = NULL;
@@ -107,10 +109,16 @@ static void crf1de_finish(crf1de_t *crf1de)
         crf1de->features = NULL;
     }
     if (crf1de->attributes != NULL) {
+        for (i = 0; i < crf1de->num_attributes; ++i) {
+            free(crf1de->attributes[i].fids);
+        }
         free(crf1de->attributes);
         crf1de->attributes = NULL;
     }
     if (crf1de->forward_trans != NULL) {
+        for (i = 0; i < crf1de->num_labels; ++i) {
+            free(crf1de->forward_trans[i].fids);
+        }
         free(crf1de->forward_trans);
         crf1de->forward_trans = NULL;
     }
@@ -917,6 +925,14 @@ static int encoder_objective_and_gradients(encoder_t *self, floatval_t *f, float
     return 0;
 }
 
+static void encoder_release(encoder_t *self)
+{
+    crf1de_t *crf1de = (crf1de_t*)self->internal;
+    crf1de_finish(crf1de);
+    free(crf1de);
+    free(self);
+}
+
 encoder_t *crf1d_create_encoder()
 {
     encoder_t *self = (encoder_t*)calloc(1, sizeof(encoder_t));
@@ -936,6 +952,7 @@ encoder_t *crf1d_create_encoder()
             self->viterbi = encoder_viterbi;
             self->partition_factor = encoder_partition_factor;
             self->objective_and_gradients = encoder_objective_and_gradients;
+            self->release = encoder_release;
             self->internal = enc;
         }
     }
diff --git a/lib/crf/src/crfsuite_internal.h b/lib/crf/src/crfsuite_internal.h
index 096998df..f338f037 100644
--- a/lib/crf/src/crfsuite_internal.h
+++ b/lib/crf/src/crfsuite_internal.h
@@ -158,6 +158,7 @@ struct tag_encoder
 
     int (*save_model)(encoder_t *self, const char *filename, const floatval_t *w, logging_t *lg);
 
+    void (*release)(encoder_t *self);
 };
 
 /**
diff --git a/lib/crf/src/crfsuite_train.c b/lib/crf/src/crfsuite_train.c
index d5886d28..f906a4ce 100644
--- a/lib/crf/src/crfsuite_train.c
+++ b/lib/crf/src/crfsuite_train.c
@@ -84,12 +84,16 @@ static void crfsuite_train_delete(crfsuite_trainer_t* self)
 {
     crfsuite_train_internal_t *tr = (crfsuite_train_internal_t*)self->internal;
     if (tr != NULL) {
+        if (tr->gm != NULL) {
+            tr->gm->release(tr->gm);
+        }
         if (tr->params != NULL) {
             tr->params->release(tr->params);
         }
         free(tr->lg);
         free(tr);
     }
+    free(self);
 }
 
 static int crfsuite_train_addref(crfsuite_trainer_t* tr)
@@ -207,6 +211,10 @@ static int crfsuite_train_train(
         gm->save_model(gm, filename, w, lg);
     }
 
+    if (0 <= holdout) {
+        dataset_finish(&testset);
+    }
+    dataset_finish(&trainset);
     free(w);
 
     return 0;
diff --git a/lib/crf/src/params.c b/lib/crf/src/params.c
index a43c35e6..27bbf1a5 100644
--- a/lib/crf/src/params.c
+++ b/lib/crf/src/params.c
@@ -84,7 +84,9 @@ static int params_release(crfsuite_params_t* params)
             free(pars->params[i].val_s);
             free(pars->params[i].help);
         }
+        free(pars->params);
         free(pars);
+        free(params);
     }
     return count;
 }
diff --git a/lib/crf/src/rumavl.c b/lib/crf/src/rumavl.c
index a587ac20..dd6ec58f 100644
--- a/lib/crf/src/rumavl.c
+++ b/lib/crf/src/rumavl.c
@@ -831,6 +831,7 @@ static RUMAVL_NODE *node_new(RUMAVL *tree, const void *record)
  *--------------------------------------------------------------------------*/
 static void node_destroy (RUMAVL *tree, RUMAVL_NODE *node)
 {
+    mem_free(tree, node->rec);
     mem_free(tree, node);
 }