diff --git a/components/dfs/src/dfs_file.c b/components/dfs/src/dfs_file.c
index f5619e2354e6154023569b63b79f62ee99f951be..614a34949466f08ebd8789c2c50a6467f8b29423 100644
--- a/components/dfs/src/dfs_file.c
+++ b/components/dfs/src/dfs_file.c
@@ -335,6 +335,9 @@ int dfs_file_lseek(struct dfs_fd *fd, rt_off_t offset)
 
     if (fd == RT_NULL)
         return -DFS_STATUS_EINVAL;
+    fs = fd->fs;
+    if (fs == RT_NULL)
+        return -DFS_STATUS_EINVAL;
     if (fs->ops->lseek == RT_NULL)
         return -DFS_STATUS_ENOSYS;
 
diff --git a/components/finsh/msh.c b/components/finsh/msh.c
index a9767058572238ed367e13af469e53b09786d14f..02cbeea196c1fdf4a71599eb6d17d009956eae8b 100644
--- a/components/finsh/msh.c
+++ b/components/finsh/msh.c
@@ -358,6 +358,9 @@ void msh_auto_complete_path(char *path)
     struct dirent *dirent = RT_NULL;
     char *full_path, *ptr, *index;
 
+    if (!path)
+        return;
+
     full_path = (char*)rt_malloc(256);
     if (full_path == RT_NULL) return; /* out of memory */
 
diff --git a/components/finsh/msh_cmd.c b/components/finsh/msh_cmd.c
index 0ec0b076216040595a5ea6abc5dfcc62804fe403..ca92ef7a6d505bf9ae87f09b3698f8bffde8abf2 100644
--- a/components/finsh/msh_cmd.c
+++ b/components/finsh/msh_cmd.c
@@ -276,6 +276,7 @@ int cmd_time(int argc, char** argv)
 }
 FINSH_FUNCTION_EXPORT_ALIAS(cmd_time, __cmd_time, Execute command with time.);
 
+#ifdef RT_USING_HEAP
 int cmd_free(int argc, char** argv)
 {
     extern void list_mem(void);
@@ -284,6 +285,7 @@ int cmd_free(int argc, char** argv)
     return 0;
 }
 FINSH_FUNCTION_EXPORT_ALIAS(cmd_free, __cmd_free, Show the memory usage in the system.);
+#endif
 
 #endif
 
diff --git a/components/libc/minilibc/stdlib.c b/components/libc/minilibc/stdlib.c
index 51cb07fee074cc1b16ccf1419b107c6bfa7c0be3..e29ae9bc2e7ebc94d954b529e18b030bbce356d8 100644
--- a/components/libc/minilibc/stdlib.c
+++ b/components/libc/minilibc/stdlib.c
@@ -54,6 +54,7 @@ long int atol(const char* s)
 	return sign?-v:v;
 }
 
+#ifdef RT_USING_HEAP
 void *malloc(size_t size)
 {
 	return rt_malloc(size);
@@ -73,5 +74,6 @@ void *calloc(size_t nelem, size_t elsize)
 {
 	return rt_calloc(nelem, elsize);
 }
+#endif
 
 #endif
diff --git a/src/timer.c b/src/timer.c
index f71e40fcd6b2964a6890c70131881193a40771df..ba2801530deb58be257910c23b846fabce5881bf 100644
--- a/src/timer.c
+++ b/src/timer.c
@@ -293,7 +293,7 @@ RTM_EXPORT(rt_timer_delete);
  */
 rt_err_t rt_timer_start(rt_timer_t timer)
 {
-    int row_lvl;
+    unsigned int row_lvl;
     rt_list_t *timer_list;
     register rt_base_t level;
     rt_list_t *row_head[RT_TIMER_SKIP_LIST_LEVEL];