diff --git a/libcomposefs/lcfs-writer-erofs.c b/libcomposefs/lcfs-writer-erofs.c
index 46817ec..e5e81aa 100644
--- a/libcomposefs/lcfs-writer-erofs.c
+++ b/libcomposefs/lcfs-writer-erofs.c
@@ -347,16 +347,17 @@ static int compute_erofs_shared_xattrs(struct lcfs_ctx_s *ctx)
 
 			ent = hash_lookup(xattr_hash, &hkey);
 			if (ent == NULL) {
-				struct hasher_xattr_s *new_ent =
+				cleanup_free struct hasher_xattr_s *new_ent =
 					calloc(1, sizeof(struct hasher_xattr_s));
 				if (new_ent == NULL) {
 					goto fail;
 				}
 				new_ent->xattr = &node->xattrs[i];
 				ent = hash_insert(xattr_hash, new_ent);
-				if (ent == NULL) {
+				if (ent == NULL)
 					goto fail;
-				}
+				assert(ent == new_ent); /* Due to result from previously run hash_lookup() */
+				new_ent = NULL;
 			}
 			ent->count++;
 		}
@@ -1598,7 +1599,7 @@ static struct lcfs_node_s *lcfs_build_node_from_image(struct lcfs_image_data *da
 	bool tailpacked;
 	size_t xattr_size;
 	struct hasher_node_s ht_entry = { nid };
-	struct hasher_node_s *new_ht_entry;
+	cleanup_free struct hasher_node_s *new_ht_entry = NULL;
 	struct hasher_node_s *existing;
 	uint64_t n_blocks;
 	uint64_t last_oob_block;
@@ -1630,9 +1631,11 @@ static struct lcfs_node_s *lcfs_build_node_from_image(struct lcfs_image_data *da
 	new_ht_entry->nid = nid;
 	new_ht_entry->node = node;
 	if (hash_insert(data->node_hash, new_ht_entry) == NULL) {
+		lcfs_node_unref(node);
 		errno = ENOMEM;
 		return NULL;
 	}
+	new_ht_entry = NULL;
 
 	if (erofs_inode_is_compact(cino)) {
 		const struct erofs_inode_compact *c = &cino->compact;
diff --git a/libcomposefs/lcfs-writer.c b/libcomposefs/lcfs-writer.c
index 806ca2d..8eab1af 100644
--- a/libcomposefs/lcfs-writer.c
+++ b/libcomposefs/lcfs-writer.c
@@ -85,6 +85,7 @@ static struct lcfs_ctx_s *lcfs_new_ctx(struct lcfs_node_s *root,
 		break;
 
 	default:
+		errno = EINVAL;
 		ret = NULL;
 	}
 
@@ -101,6 +102,7 @@ static struct lcfs_ctx_s *lcfs_new_ctx(struct lcfs_node_s *root,
 		ret->fsverity_ctx = lcfs_fsverity_context_new();
 		if (ret->fsverity_ctx == NULL) {
 			lcfs_close(ret);
+			errno = ENOMEM;
 			return NULL;
 		}
 	}
@@ -377,7 +379,6 @@ int lcfs_write_to(struct lcfs_node_s *root, struct lcfs_write_options_s *options
 
 	ctx = lcfs_new_ctx(root, options);
 	if (ctx == NULL) {
-		errno = ENOMEM;
 		return -1;
 	}
 
diff --git a/tools/mkcomposefs.c b/tools/mkcomposefs.c
index 10114a5..21b051b 100644
--- a/tools/mkcomposefs.c
+++ b/tools/mkcomposefs.c
@@ -119,7 +119,7 @@ static char *unescape_string(const char *escaped, size_t escaped_size,
 			     size_t *unescaped_size, char **err)
 {
 	const char *escaped_end = escaped + escaped_size;
-	char *res = malloc(escaped_size + 1);
+	cleanup_free char *res = malloc(escaped_size + 1);
 	if (res == NULL)
 		oom();
 	char *out = res;
@@ -184,7 +184,7 @@ static char *unescape_string(const char *escaped, size_t escaped_size,
 
 	*out = 0; /* Null terminate */
 
-	return res;
+	return steal_pointer(&res);
 }
 
 static char *unescape_optional_string(const char *escaped, size_t escaped_size,
diff --git a/tools/mountcomposefs.c b/tools/mountcomposefs.c
index 29894cb..1e01b4f 100644
--- a/tools/mountcomposefs.c
+++ b/tools/mountcomposefs.c
@@ -216,10 +216,12 @@ int main(int argc, char **argv)
 		if (options.objdirs == NULL)
 			errx(EXIT_FAILURE, "Out of memory\n");
 
-		for (i = 0, str = (char *)opt_basedir;; i++, str = NULL) {
+		for (i = 0, str = (char *)opt_basedir; i < options.n_objdirs;
+		     i++, str = NULL) {
 			token = strtok_r(str, ":", &saveptr);
 			if (token == NULL)
-				break;
+				errx(EXIT_FAILURE,
+				     "Value for basedir option has incorrect format\n");
 			options.objdirs[i] = token;
 		}
 	}