diff --git a/libs/libc/pwd/lib_getpwent.c b/libs/libc/pwd/lib_getpwent.c
index 53ac0808fe1..d1bf0d67374 100644
--- a/libs/libc/pwd/lib_getpwent.c
+++ b/libs/libc/pwd/lib_getpwent.c
@@ -154,7 +154,7 @@ int getpwent_r(FAR struct passwd *pwd,
     }
 
   ret = getpwbuf_r(ROOT_UID, ROOT_GID, ROOT_NAME, ROOT_NAME, ROOT_DIR,
-                    ROOT_SHELL, pwd, buf, buflen, result);
+                   ROOT_SHELL, pwd, buf, buflen, result);
   if (ret == 0)
     {
       g_passwd_index++;
diff --git a/libs/libc/signal/sig_altstack.c b/libs/libc/signal/sig_altstack.c
index 9d7ded47ded..e9c8e5f038c 100644
--- a/libs/libc/signal/sig_altstack.c
+++ b/libs/libc/signal/sig_altstack.c
@@ -41,7 +41,7 @@
  *
  ****************************************************************************/
 
-int sigaltstack(const stack_t *ss, stack_t *oss)
+int sigaltstack(FAR const stack_t *ss, FAR stack_t *oss)
 {
   if (ss)
     {
diff --git a/libs/libc/string/lib_strsignal.c b/libs/libc/string/lib_strsignal.c
index e4e7f4f07db..3f216851733 100644
--- a/libs/libc/string/lib_strsignal.c
+++ b/libs/libc/string/lib_strsignal.c
@@ -98,6 +98,7 @@ FAR char *strsignal(int signum)
       CASE_SIG_STR(SIGXFSZ,   "File size limit exceeded");
       CASE_SIG_STR(SIGVTALRM, "Virtual timer expired");
       CASE_SIG_STR(SIGPROF,   "Profiling timer expired");
+      CASE_SIG_STR(SIGWINCH,  "Window resize signal");
       CASE_SIG_STR(SIGPOLL,   "Pollable event occurred");
       CASE_SIG_STR(SIGSYS,    "Bad system call");
 
diff --git a/mm/umm_heap/umm_malloc.c b/mm/umm_heap/umm_malloc.c
index 97a12c22040..9727596b409 100644
--- a/mm/umm_heap/umm_malloc.c
+++ b/mm/umm_heap/umm_malloc.c
@@ -62,7 +62,7 @@ FAR void *malloc(size_t size)
   /* Use mm_malloc() because it implements the clear */
 
   ret = mm_malloc(USR_HEAP, size);
-  if (!ret)
+  if (ret == NULL)
     {
       set_errno(ENOMEM);
     }
diff --git a/mm/umm_heap/umm_memalign.c b/mm/umm_heap/umm_memalign.c
index f67cfc0cff3..c5d9236e12f 100644
--- a/mm/umm_heap/umm_memalign.c
+++ b/mm/umm_heap/umm_memalign.c
@@ -89,7 +89,7 @@ FAR void *memalign(size_t alignment, size_t size)
   FAR void *ret;
 
   ret = mm_memalign(USR_HEAP, alignment, size);
-  if (!ret)
+  if (ret == NULL)
     {
       set_errno(ENOMEM);
     }
diff --git a/mm/umm_heap/umm_realloc.c b/mm/umm_heap/umm_realloc.c
index f3c221b5288..80580f8b93f 100644
--- a/mm/umm_heap/umm_realloc.c
+++ b/mm/umm_heap/umm_realloc.c
@@ -91,7 +91,7 @@ FAR void *realloc(FAR void *oldmem, size_t size)
   FAR void *ret;
 
   ret = mm_realloc(USR_HEAP, oldmem, size);
-  if (!ret)
+  if (ret == NULL)
     {
       set_errno(ENOMEM);
     }
diff --git a/mm/umm_heap/umm_zalloc.c b/mm/umm_heap/umm_zalloc.c
index 0ff400d7fb4..7aa95e853f5 100644
--- a/mm/umm_heap/umm_zalloc.c
+++ b/mm/umm_heap/umm_zalloc.c
@@ -68,7 +68,7 @@ FAR void *zalloc(size_t size)
   /* Use mm_zalloc() because it implements the clear */
 
   ret = mm_zalloc(USR_HEAP, size);
-  if (!ret)
+  if (ret == NULL)
     {
       set_errno(ENOMEM);
     }