diff --git a/Src/stm32l4xx_hal_crc_ex.c b/Src/stm32l4xx_hal_crc_ex.c
index 6f66833..17a5851 100644
--- a/Src/stm32l4xx_hal_crc_ex.c
+++ b/Src/stm32l4xx_hal_crc_ex.c
@@ -94,44 +94,53 @@
   /* Check the parameters */
   assert_param(IS_CRC_POL_LENGTH(PolyLength));
 
-  /* check polynomial definition vs polynomial size:
-   * polynomial length must be aligned with polynomial
-   * definition. HAL_ERROR is reported if Pol degree is
-   * larger than that indicated by PolyLength.
-   * Look for MSB position: msb will contain the degree of
-   *  the second to the largest polynomial member. E.g., for
-   *  X^7 + X^6 + X^5 + X^2 + 1, msb = 6. */
-  while ((msb-- > 0U) && ((Pol & ((uint32_t)(0x1U) << (msb & 0x1FU))) == 0U))
+  /* Ensure that the generating polynomial is odd */ 
+  if ((Pol & (uint32_t)(0x1U)) ==  0U)
   {
+    status =  HAL_ERROR;
   }
-
-  switch (PolyLength)
+  else
   {
-    case CRC_POLYLENGTH_7B:
-      if (msb >= HAL_CRC_LENGTH_7B)
-      {
-        status =   HAL_ERROR;
-      }
-      break;
-    case CRC_POLYLENGTH_8B:
-      if (msb >= HAL_CRC_LENGTH_8B)
-      {
-        status =   HAL_ERROR;
-      }
-      break;
-    case CRC_POLYLENGTH_16B:
-      if (msb >= HAL_CRC_LENGTH_16B)
-      {
-        status =   HAL_ERROR;
-      }
-      break;
+    /* check polynomial definition vs polynomial size:
+     * polynomial length must be aligned with polynomial
+     * definition. HAL_ERROR is reported if Pol degree is
+     * larger than that indicated by PolyLength.
+     * Look for MSB position: msb will contain the degree of
+     *  the second to the largest polynomial member. E.g., for
+     *  X^7 + X^6 + X^5 + X^2 + 1, msb = 6. */
+    while ((msb-- > 0U) && ((Pol & ((uint32_t)(0x1U) << (msb & 0x1FU))) == 0U))
+    {
+    }
 
-    case CRC_POLYLENGTH_32B:
-      /* no polynomial definition vs. polynomial length issue possible */
-      break;
-    default:
-      status =  HAL_ERROR;
-      break;
+    switch (PolyLength)
+    {
+          
+      case CRC_POLYLENGTH_7B:
+        if (msb >= HAL_CRC_LENGTH_7B)
+        {
+          status =   HAL_ERROR;
+        }
+        break;
+      case CRC_POLYLENGTH_8B:
+        if (msb >= HAL_CRC_LENGTH_8B)
+        {
+          status =   HAL_ERROR;
+        }
+        break;
+      case CRC_POLYLENGTH_16B:
+        if (msb >= HAL_CRC_LENGTH_16B)
+        {
+          status =   HAL_ERROR;
+        }
+        break;
+ 
+      case CRC_POLYLENGTH_32B:
+        /* no polynomial definition vs. polynomial length issue possible */
+        break;
+      default:
+        status =  HAL_ERROR;
+        break;
+    }
   }
   if (status == HAL_OK)
   {