diff --git a/arch/arm/src/stm32/stm32_rng.c b/arch/arm/src/stm32/stm32_rng.c
index 6588814d6c..6d198341e3 100644
--- a/arch/arm/src/stm32/stm32_rng.c
+++ b/arch/arm/src/stm32/stm32_rng.c
@@ -246,9 +246,11 @@ static int stm32_interrupt(int irq, void *context, FAR void *arg)
 
 static ssize_t stm32_read(struct file *filep, char *buffer, size_t buflen)
 {
-  if (sem_wait(&g_rngdev.rd_devsem) != OK)
+  int ret;
+
+  if (sem_wait(&g_rngdev.rd_devsem) < 0)
     {
-      return -errno;
+      return -get_errno();
     }
   else
     {
@@ -272,13 +274,17 @@ static ssize_t stm32_read(struct file *filep, char *buffer, size_t buflen)
 
       /* Wait until the buffer is filled */
 
-      sem_wait(&g_rngdev.rd_readsem);
+      ret = sem_wait(&g_rngdev.rd_readsem);
+      if (ret < 0)
+        {
+          ret = -get_errno();
+        }
 
       /* Free RNG for next use */
 
       sem_post(&g_rngdev.rd_devsem);
 
-      return buflen;
+      return ret < 0 ? ret : buflen;
     }
 }
 
diff --git a/arch/arm/src/stm32f7/stm32_ethernet.c b/arch/arm/src/stm32f7/stm32_ethernet.c
index dac4787a8c..8c0eddd847 100644
--- a/arch/arm/src/stm32f7/stm32_ethernet.c
+++ b/arch/arm/src/stm32f7/stm32_ethernet.c
@@ -3369,6 +3369,8 @@ static int stm32_phyinit(struct stm32_ethmac_s *priv)
       default:
         nerr("ERROR: Unrecognized PHY status setting\n");
 
+        /* Falls through */
+
       case CONFIG_STM32F7_PHYSR_10HD:
         priv->fduplex = 0;
         priv->mbps100 = 0;
diff --git a/arch/arm/src/stm32f7/stm32_rng.c b/arch/arm/src/stm32f7/stm32_rng.c
index 8fb0f46685..7b746dc522 100644
--- a/arch/arm/src/stm32f7/stm32_rng.c
+++ b/arch/arm/src/stm32f7/stm32_rng.c
@@ -267,9 +267,11 @@ static int stm32_rnginterrupt(int irq, void *context, FAR void *arg)
 
 static ssize_t stm32_rngread(struct file *filep, char *buffer, size_t buflen)
 {
-  if (sem_wait(&g_rngdev.rd_devsem) != OK)
+  int ret;
+
+  if (sem_wait(&g_rngdev.rd_devsem) < 0)
     {
-      return -errno;
+      return -get_errno();
     }
   else
     {
@@ -293,7 +295,11 @@ static ssize_t stm32_rngread(struct file *filep, char *buffer, size_t buflen)
 
       /* Wait until the buffer is filled */
 
-      sem_wait(&g_rngdev.rd_readsem);
+      ret = sem_wait(&g_rngdev.rd_readsem);
+      if (ret < 0)
+        {
+          ret = -get_errno();
+        }
 
       /* Done with the operation semaphore */
 
@@ -303,7 +309,7 @@ static ssize_t stm32_rngread(struct file *filep, char *buffer, size_t buflen)
 
       sem_post(&g_rngdev.rd_devsem);
 
-      return buflen;
+      return ret < 0 ? ret : buflen;
     }
 }