diff --git a/portable/MemMang/heap_2.c b/portable/MemMang/heap_2.c
index 1240a6b53..1eed436ce 100644
--- a/portable/MemMang/heap_2.c
+++ b/portable/MemMang/heap_2.c
@@ -138,7 +138,7 @@ void * pvPortMalloc( size_t xWantedSize )
         {
             /* Ensure xWantedSize will never wrap after adjustment, even if we need
              * an alignment adjustment */
-            if ( xWantedSize < ( SIZE_MAX - heapSTRUCT_SIZE - portBYTE_ALIGNMENT - 1) )
+            if( ( xWantedSize > 0 ) && ( ( xWantedSize + xHeapStructSize ) >  xWantedSize ) )
             {
                 xWantedSize += heapSTRUCT_SIZE;
 
@@ -154,7 +154,7 @@ void * pvPortMalloc( size_t xWantedSize )
             }
         }
 
-        if( xWantedSize > 0 )
+        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 8bdedf767..a86052c20 100644
--- a/portable/MemMang/heap_4.c
+++ b/portable/MemMang/heap_4.c
@@ -176,7 +176,7 @@ void * pvPortMalloc( size_t xWantedSize )
                 mtCOVERAGE_TEST_MARKER();
             }
 
-            if( ( xWantedSize > 0 ) && ( xWantedSize < xFreeBytesRemaining ) )
+            if( ( xWantedSize > 0 ) && ( xWantedSize <= xFreeBytesRemaining ) )
             {
                 /* Traverse the list from the start	(lowest address) block until
                  * one of adequate size is found. */
diff --git a/portable/MemMang/heap_5.c b/portable/MemMang/heap_5.c
index 4953237f0..c4d96cb44 100644
--- a/portable/MemMang/heap_5.c
+++ b/portable/MemMang/heap_5.c
@@ -179,7 +179,7 @@ void * pvPortMalloc( size_t xWantedSize )
                 xWantedSize = 0;
             }
 
-            if( ( xWantedSize > 0 ) && ( xWantedSize < xFreeBytesRemaining ) )
+            if( ( xWantedSize > 0 ) && ( xWantedSize <= xFreeBytesRemaining ) )
             {
                 /* Traverse the list from the start	(lowest address) block until
                  * one of adequate size is found. */