diff --git a/src/ports/STM32Cube/pnal.c b/src/ports/STM32Cube/pnal.c
index 7f7d3f6e..a6ac3324 100644
--- a/src/ports/STM32Cube/pnal.c
+++ b/src/ports/STM32Cube/pnal.c
@@ -299,7 +299,9 @@ pnal_buf_t * pnal_buf_alloc (uint16_t length)
 
 void pnal_buf_free (pnal_buf_t * p)
 {
-   CC_ASSERT (pbuf_free (p) == 1);
+   u8_t ret = pbuf_free (p);
+   CC_UNUSED (ret);
+   CC_ASSERT (ret == 1);
 }
 
 uint8_t pnal_buf_header (pnal_buf_t * p, int16_t header_size_increment)
diff --git a/src/ports/iMX8M/pnal.c b/src/ports/iMX8M/pnal.c
index cf1efaad..9a5d2343 100644
--- a/src/ports/iMX8M/pnal.c
+++ b/src/ports/iMX8M/pnal.c
@@ -176,7 +176,9 @@ pnal_buf_t * pnal_buf_alloc (uint16_t length)
 
 void pnal_buf_free (pnal_buf_t * p)
 {
-   CC_ASSERT (pbuf_free (p) == 1);
+   u8_t ret = pbuf_free (p);
+   CC_UNUSED (ret);
+   CC_ASSERT (ret == 1);
 }
 
 uint8_t pnal_buf_header (pnal_buf_t * p, int16_t header_size_increment)
diff --git a/src/ports/rt-kernel/pnal.c b/src/ports/rt-kernel/pnal.c
index 214ef7bf..aae7f007 100644
--- a/src/ports/rt-kernel/pnal.c
+++ b/src/ports/rt-kernel/pnal.c
@@ -368,8 +368,10 @@ pnal_buf_t * pnal_buf_alloc (uint16_t length)
 }
 
 void pnal_buf_free (pnal_buf_t * p)
-{
-   ASSERT (pbuf_free (p) == 1);
+{ 
+   u8_t ret = pbuf_free (p);
+   (void)ret;
+   ASSERT (ret == 1);
 }
 
 uint8_t pnal_buf_header (pnal_buf_t * p, int16_t header_size_increment)