diff --git a/xen/arch/x86/dmi_scan.c b/xen/arch/x86/dmi_scan.c
index 81f80c053a..b517c068b8 100644
--- a/xen/arch/x86/dmi_scan.c
+++ b/xen/arch/x86/dmi_scan.c
@@ -113,6 +113,7 @@ static const void *__init bt_ioremap(paddr_t addr, unsigned int len)
 {
     mfn_t mfn = _mfn(PFN_DOWN(addr));
     unsigned int offs = PAGE_OFFSET(addr);
+    void *va;
 
     if ( addr + len <= MB(1) )
         return __va(addr);
@@ -120,8 +121,10 @@ static const void *__init bt_ioremap(paddr_t addr, unsigned int len)
     if ( system_state < SYS_STATE_boot )
         return __acpi_map_table(addr, len);
 
-    return __vmap(&mfn, PFN_UP(offs + len), 1, 1, PAGE_HYPERVISOR_RO,
-                  VMAP_DEFAULT) + offs;
+    va = __vmap(&mfn, PFN_UP(offs + len), 1, 1, PAGE_HYPERVISOR_RO,
+                VMAP_DEFAULT);
+
+    return va ? va + offs : NULL;
 }
 
 static void __init bt_iounmap(const void *ptr, unsigned int len)
diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 2f0e586463..1454a18fc2 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -5994,7 +5994,9 @@ void __iomem *ioremap(paddr_t pa, size_t len)
         unsigned int offs = pa & (PAGE_SIZE - 1);
         unsigned int nr = PFN_UP(offs + len);
 
-        va = __vmap(&mfn, nr, 1, 1, PAGE_HYPERVISOR_UCMINUS, VMAP_DEFAULT) + offs;
+        va = __vmap(&mfn, nr, 1, 1, PAGE_HYPERVISOR_UCMINUS, VMAP_DEFAULT);
+        if ( va )
+            va += offs;
     }
 
     return (void __force __iomem *)va;
@@ -6011,7 +6013,7 @@ void __iomem *__init ioremap_wc(paddr_t pa, size_t len)
 
     va = __vmap(&mfn, nr, 1, 1, PAGE_HYPERVISOR_WC, VMAP_DEFAULT);
 
-    return (void __force __iomem *)(va + offs);
+    return (void __force __iomem *)(va ? va + offs : NULL);
 }
 
 int create_perdomain_mapping(struct domain *d, unsigned long va,