diff --git a/gklearn/kernels/common_walk.py b/gklearn/kernels/common_walk.py
index 505dc18..0aeb3ee 100644
--- a/gklearn/kernels/common_walk.py
+++ b/gklearn/kernels/common_walk.py
@@ -86,17 +86,12 @@ class CommonWalk(GraphKernel):
 		elif self.__compute_method == 'geo':
 			do_fun = self._wrapper_kernel_do_geo
 			
-		parallel_gm(do_fun, gram_matrix, self._graphs, init_worker=self._init_worker_gm, 
+		parallel_gm(do_fun, gram_matrix, self._graphs, init_worker=_init_worker_gm, 
 			  glbv=(self._graphs,), n_jobs=self._n_jobs, verbose=self._verbose)
 			
 		return gram_matrix
 	
 	
-	def _init_worker_gm(gn_toshare):
-		global G_gn
-		G_gn = gn_toshare
-	
-	
 	def _compute_kernel_list_series(self, g1, g_list):
 		self.__check_graphs(g_list + [g1])
 		self.__add_dummy_labels(g_list + [g1])
@@ -152,19 +147,12 @@ class CommonWalk(GraphKernel):
 		itr = range(len(g_list))
 		len_itr = len(g_list)
 		parallel_me(do_fun, func_assign, kernel_list, itr, len_itr=len_itr,
-			init_worker=self._init_worker_list, glbv=(g1, g_list), method='imap_unordered', 
+			init_worker=_init_worker_list, glbv=(g1, g_list), method='imap_unordered', 
 			n_jobs=self._n_jobs, itr_desc='calculating kernels', verbose=self._verbose)
 			
 		return kernel_list
 	
 	
-	def _init_worker_list(g1_toshare, g_list_toshare):
-		global G_g1, G_g_list
-		G_g1 = g1_toshare
-		G_g_list = g_list_toshare
-
-	
-	
 	def _wrapper_kernel_list_do_exp(self, itr):
 		return itr, self.__kernel_do_exp(G_g1, G_g_list[itr], self.__weight)
 
@@ -291,4 +279,15 @@ class CommonWalk(GraphKernel):
 		if len(self.__edge_labels) == 0 or (len(self.__edge_labels) == 1 and self.__edge_labels[0] == SpecialLabel.DUMMY):
 			for i in range(len(Gn)):
 				nx.set_edge_attributes(Gn[i], '0', SpecialLabel.DUMMY)
-			self.__edge_labels = [SpecialLabel.DUMMY]
\ No newline at end of file
+			self.__edge_labels = [SpecialLabel.DUMMY]
+			
+			
+def _init_worker_gm(gn_toshare):
+	global G_gn
+	G_gn = gn_toshare
+	
+	
+def _init_worker_list(g1_toshare, g_list_toshare):
+	global G_g1, G_g_list
+	G_g1 = g1_toshare
+	G_g_list = g_list_toshare
\ No newline at end of file