diff --git a/portable/MemMang/heap_1.c b/portable/MemMang/heap_1.c
index 4a7f8c2..2b73463 100644
--- a/portable/MemMang/heap_1.c
+++ b/portable/MemMang/heap_1.c
@@ -22,7 +22,6 @@
  * https://www.FreeRTOS.org
  * https://github.com/FreeRTOS
  *
- * 1 tab == 4 spaces!
  */
 
 
@@ -72,13 +71,20 @@
     void * pvReturn = NULL;
     static uint8_t * pucAlignedHeap = NULL;
 
-    /* Ensure that blocks are always aligned to the required number of bytes. */
+    /* Ensure that blocks are always aligned. */
     #if ( portBYTE_ALIGNMENT != 1 )
         {
             if( xWantedSize & portBYTE_ALIGNMENT_MASK )
             {
-                /* Byte alignment required. */
-                xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) );
+                /* Byte alignment required. Check for overflow. */
+                if ( (xWantedSize + ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) )) > xWantedSize )
+                {
+                    xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) );
+                } 
+                else 
+                {
+                    xWantedSize = 0;
+                }
             }
         }
     #endif
@@ -91,8 +97,9 @@
             pucAlignedHeap = ( uint8_t * ) ( ( ( portPOINTER_SIZE_TYPE ) & ucHeap[ portBYTE_ALIGNMENT ] ) & ( ~( ( portPOINTER_SIZE_TYPE ) portBYTE_ALIGNMENT_MASK ) ) );
         }
 
-        /* Check there is enough room left for the allocation. */
-        if( ( ( xNextFreeByte + xWantedSize ) < configADJUSTED_HEAP_SIZE ) &&
+        /* Check there is enough room left for the allocation and. */
+        if( ( xWantedSize > 0 ) && /* valid size */
+            ( ( xNextFreeByte + xWantedSize ) < configADJUSTED_HEAP_SIZE ) &&
             ( ( xNextFreeByte + xWantedSize ) > xNextFreeByte ) ) /* Check for overflow. */
         {
             /* Return the next free byte then increment the index past this
diff --git a/portable/MemMang/heap_2.c b/portable/MemMang/heap_2.c
index 640cd54..e132ae3 100644
--- a/portable/MemMang/heap_2.c
+++ b/portable/MemMang/heap_2.c
@@ -22,7 +22,6 @@
  * https://www.FreeRTOS.org
  * https://github.com/FreeRTOS
  *
- * 1 tab == 4 spaces!
  */
 
 /*
@@ -132,21 +131,32 @@
             xHeapHasBeenInitialised = pdTRUE;
         }
 
-        /* The wanted size is increased so it can contain a BlockLink_t
+        /* The wanted size must be increased so it can contain a BlockLink_t
          * structure in addition to the requested amount of bytes. */
-        if( xWantedSize > 0 )
+        if( ( xWantedSize > 0 ) && 
+            ( ( xWantedSize + heapSTRUCT_SIZE ) >  xWantedSize ) ) /* Overflow check */
         {
             xWantedSize += heapSTRUCT_SIZE;
 
-            /* Ensure that blocks are always aligned to the required number of bytes. */
-            if( ( xWantedSize & portBYTE_ALIGNMENT_MASK ) != 0 )
+            /* Byte alignment required. Check for overflow. */
+            if( ( xWantedSize + ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) ) ) 
+                    > xWantedSize )
             {
-                /* Byte alignment required. */
                 xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) );
+                configASSERT( ( xWantedSize & portBYTE_ALIGNMENT_MASK ) == 0 );
             }
+            else
+            {
+                xWantedSize = 0;
+            }       
+        }
+        else 
+        {
+            xWantedSize = 0; 
         }
 
-        if( ( xWantedSize > 0 ) && ( xWantedSize < configADJUSTED_HEAP_SIZE ) )
+
+        if( ( xWantedSize > 0 ) && ( xWantedSize <= xFreeBytesRemaining ) )
         {
             /* Blocks are stored in byte order - traverse the list from the start
              * (smallest) block until one of adequate size is found. */
diff --git a/portable/MemMang/heap_4.c b/portable/MemMang/heap_4.c
index 7e5357c..2a1ee20 100644
--- a/portable/MemMang/heap_4.c
+++ b/portable/MemMang/heap_4.c
@@ -136,34 +136,42 @@
          * kernel, so it must be free. */
         if( ( xWantedSize & xBlockAllocatedBit ) == 0 )
         {
-            /* The wanted size is increased so it can contain a BlockLink_t
+            /* The wanted size must be increased so it can contain a BlockLink_t
              * structure in addition to the requested amount of bytes. */
-            if( xWantedSize > 0 )
+            if( ( xWantedSize > 0 ) && 
+                ( ( xWantedSize + xHeapStructSize ) >  xWantedSize ) ) /* Overflow check */
             {
                 xWantedSize += xHeapStructSize;
 
-                /* Ensure that blocks are always aligned to the required number
-                 * of bytes. */
+                /* Ensure that blocks are always aligned. */
                 if( ( xWantedSize & portBYTE_ALIGNMENT_MASK ) != 0x00 )
                 {
-                    /* Byte alignment required. */
-                    xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) );
-                    configASSERT( ( xWantedSize & portBYTE_ALIGNMENT_MASK ) == 0 );
+                    /* Byte alignment required. Check for overflow. */
+                    if( ( xWantedSize + ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) ) ) 
+                            > xWantedSize )
+                    {
+                        xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) );
+                        configASSERT( ( xWantedSize & portBYTE_ALIGNMENT_MASK ) == 0 );
+                    }
+                    else
+                    {
+                        xWantedSize = 0;
+                    }  
                 }
                 else
                 {
                     mtCOVERAGE_TEST_MARKER();
                 }
-            }
-            else
+            } 
+            else 
             {
-                mtCOVERAGE_TEST_MARKER();
+                xWantedSize = 0;
             }
 
             if( ( xWantedSize > 0 ) && ( xWantedSize <= xFreeBytesRemaining ) )
             {
                 /* Traverse the list from the start	(lowest address) block until
-                 * one	of adequate size is found. */
+                 * one of adequate size is found. */
                 pxPreviousBlock = &xStart;
                 pxBlock = xStart.pxNextFreeBlock;
 
@@ -174,7 +182,7 @@
                 }
 
                 /* If the end marker was reached then a block of adequate size
-                 * was	not found. */
+                 * was not found. */
                 if( pxBlock != pxEnd )
                 {
                     /* Return the memory space pointed to - jumping over the
diff --git a/portable/MemMang/heap_5.c b/portable/MemMang/heap_5.c
index 90c0b5b..fe194a6 100644
--- a/portable/MemMang/heap_5.c
+++ b/portable/MemMang/heap_5.c
@@ -22,7 +22,6 @@
  * https://www.FreeRTOS.org
  * https://github.com/FreeRTOS
  *
- * 1 tab == 4 spaces!
  */
 
 /*
@@ -150,16 +149,24 @@
         {
             /* The wanted size is increased so it can contain a BlockLink_t
              * structure in addition to the requested amount of bytes. */
-            if( xWantedSize > 0 )
+            if( ( xWantedSize > 0 ) && 
+                ( ( xWantedSize + xHeapStructSize ) >  xWantedSize ) ) /* Overflow check */
             {
                 xWantedSize += xHeapStructSize;
 
-                /* Ensure that blocks are always aligned to the required number
-                 * of bytes. */
+                /* Ensure that blocks are always aligned */
                 if( ( xWantedSize & portBYTE_ALIGNMENT_MASK ) != 0x00 )
                 {
-                    /* Byte alignment required. */
-                    xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) );
+                    /* Byte alignment required. Check for overflow */
+                    if( ( xWantedSize + ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) ) ) >
+                         xWantedSize )
+                    {
+                        xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) );
+                    } 
+                    else 
+                    {
+                        xWantedSize = 0;
+                    }
                 }
                 else
                 {
@@ -168,13 +175,13 @@
             }
             else
             {
-                mtCOVERAGE_TEST_MARKER();
+                xWantedSize = 0;
             }
 
             if( ( xWantedSize > 0 ) && ( xWantedSize <= xFreeBytesRemaining ) )
             {
                 /* Traverse the list from the start	(lowest address) block until
-                 * one	of adequate size is found. */
+                 * one of adequate size is found. */
                 pxPreviousBlock = &xStart;
                 pxBlock = xStart.pxNextFreeBlock;
 
@@ -185,7 +192,7 @@
                 }
 
                 /* If the end marker was reached then a block of adequate size
-                 * was	not found. */
+                 * was not found. */
                 if( pxBlock != pxEnd )
                 {
                     /* Return the memory space pointed to - jumping over the