diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
index 4bb11960ee..9469c9d08c 100644
--- a/xen/arch/arm/gic.c
+++ b/xen/arch/arm/gic.c
@@ -134,8 +134,7 @@ int gic_route_irq_to_guest(struct domain *d, unsigned int virq,
 
     ASSERT(spin_is_locked(&desc->lock));
     /* Caller has already checked that the IRQ is an SPI */
-    ASSERT(virq >= 32);
-    ASSERT(virq < vgic_num_irqs(d));
+    ASSERT(vgic_is_spi(d, virq));
     ASSERT(!is_lpi(virq));
 
     ret = vgic_connect_hw_irq(d, NULL, virq, desc, true);
diff --git a/xen/arch/arm/include/asm/vgic.h b/xen/arch/arm/include/asm/vgic.h
index 35c0c6a8b0..3e7cbbb196 100644
--- a/xen/arch/arm/include/asm/vgic.h
+++ b/xen/arch/arm/include/asm/vgic.h
@@ -335,6 +335,13 @@ extern void vgic_check_inflight_irqs_pending(struct vcpu *v,
 /* Default number of vGIC SPIs. 32 are substracted to cover local IRQs. */
 #define VGIC_DEF_NR_SPIS (min(gic_number_lines(), VGIC_MAX_IRQS) - 32)
 
+extern bool vgic_is_valid_line(struct domain *d, unsigned int virq);
+
+static inline bool vgic_is_spi(struct domain *d, unsigned int virq)
+{
+    return virq >= NR_LOCAL_IRQS && vgic_is_valid_line(d, virq);
+}
+
 /*
  * Allocate a guest VIRQ
  *  - spi == 0 => allocate a PPI. It will be the same on every vCPU
diff --git a/xen/arch/arm/irq.c b/xen/arch/arm/irq.c
index 29524e5d53..0df1e0a7c1 100644
--- a/xen/arch/arm/irq.c
+++ b/xen/arch/arm/irq.c
@@ -445,7 +445,7 @@ int route_irq_to_guest(struct domain *d, unsigned int virq,
     unsigned long flags;
     int retval = 0;
 
-    if ( virq >= vgic_num_irqs(d) )
+    if ( !vgic_is_valid_line(d, virq) )
     {
         printk(XENLOG_G_ERR
                "the vIRQ number %u is too high for domain %u (max = %u)\n",
@@ -563,7 +563,7 @@ int release_guest_irq(struct domain *d, unsigned int virq)
     int ret;
 
     /* Only SPIs are supported */
-    if ( virq < NR_LOCAL_IRQS || virq >= vgic_num_irqs(d) )
+    if ( !vgic_is_spi(d, virq) )
         return -EINVAL;
 
     desc = vgic_get_hw_irq_desc(d, NULL, virq);
diff --git a/xen/arch/arm/vgic.c b/xen/arch/arm/vgic.c
index c563ba93af..2bbf4d99aa 100644
--- a/xen/arch/arm/vgic.c
+++ b/xen/arch/arm/vgic.c
@@ -24,6 +24,12 @@
 #include <asm/gic.h>
 #include <asm/vgic.h>
 
+
+bool vgic_is_valid_line(struct domain *d, unsigned int virq)
+{
+    return virq < vgic_num_irqs(d);
+}
+
 static inline struct vgic_irq_rank *vgic_get_rank(struct vcpu *v,
                                                   unsigned int rank)
 {
@@ -582,7 +588,7 @@ void vgic_inject_irq(struct domain *d, struct vcpu *v, unsigned int virq,
     if ( !v )
     {
         /* The IRQ needs to be an SPI if no vCPU is specified. */
-        ASSERT(virq >= 32 && virq <= vgic_num_irqs(d));
+        ASSERT(vgic_is_spi(d, virq));
 
         v = vgic_get_target_vcpu(d->vcpu[0], virq);
     };
@@ -659,7 +665,7 @@ bool vgic_emulate(struct cpu_user_regs *regs, union hsr hsr)
 
 bool vgic_reserve_virq(struct domain *d, unsigned int virq)
 {
-    if ( virq >= vgic_num_irqs(d) )
+    if ( !vgic_is_valid_line(d, virq) )
         return false;
 
     return !test_and_set_bit(virq, d->arch.vgic.allocated_irqs);
diff --git a/xen/arch/arm/vgic/vgic.c b/xen/arch/arm/vgic/vgic.c
index 6cabd0496d..b2c0e1873a 100644
--- a/xen/arch/arm/vgic/vgic.c
+++ b/xen/arch/arm/vgic/vgic.c
@@ -718,6 +718,11 @@ bool vgic_reserve_virq(struct domain *d, unsigned int virq)
     return !test_and_set_bit(virq, d->arch.vgic.allocated_irqs);
 }
 
+bool vgic_is_valid_line(struct domain *d, unsigned int virq)
+{
+    return virq < vgic_num_irqs(d);
+}
+
 int vgic_allocate_virq(struct domain *d, bool spi)
 {
     int first, end;