diff --git a/xen/common/gunzip.c b/xen/common/gunzip.c
index db4efcd34b..425d64e904 100644
--- a/xen/common/gunzip.c
+++ b/xen/common/gunzip.c
@@ -114,11 +114,16 @@ __init int perform_gunzip(char *output, char *image, unsigned long image_len)
     window = (unsigned char *)output;
 
     free_mem_ptr = (unsigned long)alloc_xenheap_pages(HEAPORDER, 0);
+    if ( !free_mem_ptr )
+        return -ENOMEM;
+
     free_mem_end_ptr = free_mem_ptr + (PAGE_SIZE << HEAPORDER);
+    init_allocator();
 
     inbuf = (unsigned char *)image;
     insize = image_len;
     inptr = 0;
+    bytes_out = 0;
 
     makecrc();
 
diff --git a/xen/common/inflate.c b/xen/common/inflate.c
index f99c985d61..d8c28a3e95 100644
--- a/xen/common/inflate.c
+++ b/xen/common/inflate.c
@@ -238,6 +238,12 @@ STATIC const ush mask_bits[] = {
 static unsigned long INITDATA malloc_ptr;
 static int INITDATA malloc_count;
 
+static void init_allocator(void)
+{
+    malloc_ptr = free_mem_ptr;
+    malloc_count = 0;
+}
+
 static void *INIT malloc(int size)
 {
     void *p;