diff --git a/drivers/wireless/cc3000/cc3000.c b/drivers/wireless/cc3000/cc3000.c
index 2c113b4f28..63b5d98cc9 100644
--- a/drivers/wireless/cc3000/cc3000.c
+++ b/drivers/wireless/cc3000/cc3000.c
@@ -687,7 +687,7 @@ static void * cc3000_worker(FAR void *arg)
                      * Will it fit?
                      */
 
-                    if (data_to_recv >= priv->rx_buffer_max_len
+                    if (data_to_recv >= priv->rx_buffer_max_len)
                       {
                         lowsyslog(LOG_INFO, "data_to_recv %d", data_to_recv);
                       }
diff --git a/fs/aio/aio_read.c b/fs/aio/aio_read.c
index 1048954364..fd05edbc6b 100644
--- a/fs/aio/aio_read.c
+++ b/fs/aio/aio_read.c
@@ -96,7 +96,7 @@ static void aio_read_worker(FAR void *arg)
 #ifdef CONFIG_PRIORITY_INHERITANCE
   uint8_t prio;
 #endif
-  ssize_t nread;
+  ssize_t nread = 0;
 
   /* Get the information from the container, decant the AIO control block,
    * and free the container before starting any I/O.  That will minimize
diff --git a/fs/aio/aio_write.c b/fs/aio/aio_write.c
index f05e357c33..6b89038950 100644
--- a/fs/aio/aio_write.c
+++ b/fs/aio/aio_write.c
@@ -113,8 +113,10 @@ static void aio_write_worker(FAR void *arg)
 #ifdef CONFIG_PRIORITY_INHERITANCE
   uint8_t prio;
 #endif
-  ssize_t nwritten;
+  ssize_t nwritten = 0;
+#ifdef AIO_HAVE_FILEP
   int oflags;
+#endif
 
   /* Get the information from the container, decant the AIO control block,
    * and free the container before starting any I/O.  That will minimize
diff --git a/fs/fat/fs_configfat.c b/fs/fat/fs_configfat.c
index 5aff493c90..59e174ef58 100644
--- a/fs/fat/fs_configfat.c
+++ b/fs/fat/fs_configfat.c
@@ -950,7 +950,7 @@ int mkfatfs_configfatfs(FAR struct fat_format_s *fmt,
         {
           /* There must be reserved sectors in order to have a backup boot sector */
 
-          if (fmt->ff_rsvdseccount > 0 && fmt->ff_rsvdseccount >= 2)
+          if (fmt->ff_rsvdseccount >= 2)
             {
               /* Sector 0 is the MBR; 1... ff_rsvdseccount are reserved.  Try the next
                * the last reserved sector.
diff --git a/fs/nxffs/nxffs_dump.c b/fs/nxffs/nxffs_dump.c
index 181aaaebed..19e4d4b5ce 100644
--- a/fs/nxffs/nxffs_dump.c
+++ b/fs/nxffs/nxffs_dump.c
@@ -67,7 +67,9 @@ struct nxffs_blkinfo_s
   off_t nblocks;
   off_t block;
   off_t offset;
+#if defined(CONFIG_DEBUG) && defined(CONFIG_DEBUG_FS)
   bool verbose;
+#endif
 };
 
 /****************************************************************************
diff --git a/fs/nxffs/nxffs_initialize.c b/fs/nxffs/nxffs_initialize.c
index 3fb9e2b775..d7d55f077a 100644
--- a/fs/nxffs/nxffs_initialize.c
+++ b/fs/nxffs/nxffs_initialize.c
@@ -410,7 +410,7 @@ int nxffs_limits(FAR struct nxffs_volume_s *volume)
 
   if (!noinodes)
     {
-      while ((ret = nxffs_nextentry(volume, offset, &entry)) == OK)
+      while (nxffs_nextentry(volume, offset, &entry) == OK)
         {
           /* Discard the entry and guess the next offset. */
 
diff --git a/fs/smartfs/smartfs_procfs.c b/fs/smartfs/smartfs_procfs.c
index 2b56f366d9..e74d659447 100644
--- a/fs/smartfs/smartfs_procfs.c
+++ b/fs/smartfs/smartfs_procfs.c
@@ -709,7 +709,9 @@ static size_t smartfs_status_read(FAR struct file *filep, FAR char *buffer,
   FAR struct smartfs_file_s *priv;
   int       ret;
   size_t    len;
+#if 0 /* Not used */
   int       utilization;
+#endif
 
   priv = (FAR struct smartfs_file_s *) filep->f_priv;
 
@@ -729,6 +731,7 @@ static size_t smartfs_status_read(FAR struct file *filep, FAR char *buffer,
 
       if (ret == OK)
         {
+#if 0 /* Not used */
           /* Calculate the sector utilization percentage */
 
           if (procfs_data.blockerases == 0)
@@ -741,6 +744,7 @@ static size_t smartfs_status_read(FAR struct file *filep, FAR char *buffer,
                 procfs_data.unusedsectors) / (procfs_data.blockerases *
                 procfs_data.sectorsperblk);
             }
+#endif
 
           /* Format and return data in the buffer */
 
@@ -756,8 +760,10 @@ static size_t smartfs_status_read(FAR struct file *filep, FAR char *buffer,
                   procfs_data.formatsector, procfs_data.dirsector,
                   procfs_data.freesectors, procfs_data.releasesectors,
                   procfs_data.sectorsperblk);
-                  //procfs_data.unusedsectors, procfs_data.blockerases,
-                  //procfs_data.sectorsperblk, utilization);
+#if 0 /* Not used */
+                  procfs_data.unusedsectors, procfs_data.blockerases,
+                  procfs_data.sectorsperblk, utilization);
+#endif
         }
 
       /* Indicate we have already provided all the data */
diff --git a/fs/smartfs/smartfs_smart.c b/fs/smartfs/smartfs_smart.c
index bcbda7de8e..0b9a373b15 100644
--- a/fs/smartfs/smartfs_smart.c
+++ b/fs/smartfs/smartfs_smart.c
@@ -1441,7 +1441,7 @@ static int smartfs_unbind(void *handle, FAR struct inode **blkdriver)
 static int smartfs_statfs(struct inode *mountpt, struct statfs *buf)
 {
   struct smartfs_mountpt_s *fs;
-  int                   ret = OK;
+  int ret;
 
   /* Sanity checks */
 
@@ -1483,11 +1483,11 @@ static int smartfs_statfs(struct inode *mountpt, struct statfs *buf)
 
 static int smartfs_unlink(struct inode *mountpt, const char *relpath)
 {
-  struct smartfs_mountpt_s       *fs;
-  int                             ret = OK;
-  struct smartfs_entry_s          entry;
-  const char                     *filename;
-  uint16_t                        parentdirsector;
+  struct smartfs_mountpt_s *fs;
+  int                       ret;
+  struct smartfs_entry_s    entry;
+  const char               *filename;
+  uint16_t                  parentdirsector;
 
   /* Sanity checks */
 
@@ -1627,11 +1627,11 @@ errout_with_semaphore:
 
 int smartfs_rmdir(struct inode *mountpt, const char *relpath)
 {
-  struct smartfs_mountpt_s       *fs;
-  int                             ret = OK;
-  struct smartfs_entry_s          entry;
-  const char                     *filename;
-  uint16_t                        parentdirsector;
+  struct smartfs_mountpt_s *fs;
+  int                       ret;
+  struct smartfs_entry_s    entry;
+  const char               *filename;
+  uint16_t                  parentdirsector;
 
   /* Sanity checks */
 
@@ -1916,7 +1916,7 @@ static int smartfs_stat(struct inode *mountpt, const char *relpath, struct stat
 {
   struct smartfs_mountpt_s *fs;
   struct smartfs_entry_s    entry;
-  int                       ret = -ENOENT;
+  int                       ret;
   uint16_t                  parentdirsector;
   const char               *filename;
 
diff --git a/libc/net/lib_inetpton.c b/libc/net/lib_inetpton.c
index 2805a70476..8b058e044b 100644
--- a/libc/net/lib_inetpton.c
+++ b/libc/net/lib_inetpton.c
@@ -147,7 +147,7 @@ int inet_pton(int af, FAR const char *src, FAR void *dst)
               break;
             }
 
-          if (numoffset <= 0)
+          if (numoffset < 1)
             {
               /* Empty numeric string */
 
@@ -245,7 +245,7 @@ int inet_pton(int af, FAR const char *src, FAR void *dst)
               break;
             }
 
-          if (ch != '\0' && numoffset <= 0)
+          if (ch != '\0' && numoffset < 1)
             {
               /* Empty numeric string */
 
diff --git a/libc/stdio/lib_lowinstream.c b/libc/stdio/lib_lowinstream.c
index 7284601e8e..8c11fee907 100644
--- a/libc/stdio/lib_lowinstream.c
+++ b/libc/stdio/lib_lowinstream.c
@@ -65,7 +65,7 @@ static int lowinstream_getc(FAR struct lib_instream_s *this)
 
   /* Get the next character from the incoming stream */
 
-  ret = up_getc(ch)
+  ret = up_getc(ch);
   if (ret != EOF)
     {
       this->nget++;
diff --git a/libc/stdlib/lib_mkstemp.c b/libc/stdlib/lib_mkstemp.c
index 729dfa5354..94b6dcc0af 100644
--- a/libc/stdlib/lib_mkstemp.c
+++ b/libc/stdlib/lib_mkstemp.c
@@ -149,9 +149,7 @@ static void incr_base62(void)
 
 static void get_base62(FAR uint8_t *ptr)
 {
-  int ret;
-
-  while ((ret = sem_wait(&g_b62sem)) < 0)
+  while (sem_wait(&g_b62sem) < 0)
     {
       DEBUGASSERT(errno == EINTR);
     }
diff --git a/libc/stdlib/lib_qsort.c b/libc/stdlib/lib_qsort.c
index 0579b15100..0ce30e9997 100644
--- a/libc/stdlib/lib_qsort.c
+++ b/libc/stdlib/lib_qsort.c
@@ -213,6 +213,7 @@ loop:
               swap(pl, pl - size);
             }
         }
+
       return;
     }
 
@@ -230,6 +231,7 @@ loop:
   if ((r = pd - pc) > size)
     {
       /* Iterate rather than recurse to save stack space */
+
       base = pn - r;
       nmemb = r / size;
       goto loop;
diff --git a/mm/mm_heap/mm_malloc.c b/mm/mm_heap/mm_malloc.c
index 20b1916c8b..9890e5712c 100644
--- a/mm/mm_heap/mm_malloc.c
+++ b/mm/mm_heap/mm_malloc.c
@@ -91,7 +91,7 @@ FAR void *mm_malloc(FAR struct mm_heap_s *heap, size_t size)
 
   /* Handle bad sizes */
 
-  if (size <= 0)
+  if (size < 1)
     {
       return NULL;
     }
diff --git a/mm/mm_heap/mm_realloc.c b/mm/mm_heap/mm_realloc.c
index f41d019b5e..5778975f50 100644
--- a/mm/mm_heap/mm_realloc.c
+++ b/mm/mm_heap/mm_realloc.c
@@ -101,7 +101,7 @@ FAR void *mm_realloc(FAR struct mm_heap_s *heap, FAR void *oldmem,
 
   /* If size is zero, then realloc is equivalent to free */
 
-  if (size <= 0)
+  if (size < 1)
     {
       mm_free(heap, oldmem);
       return NULL;
@@ -170,7 +170,7 @@ FAR void *mm_realloc(FAR struct mm_heap_s *heap, FAR void *oldmem,
        * previous chunk is smaller than the next chunk.
        */
 
-      if (prevsize > 0 && (nextsize >= prevsize || nextsize <= 0))
+      if (prevsize > 0 && (nextsize >= prevsize || nextsize < 1))
         {
           /* Can we get everything we need from the previous chunk? */