diff --git a/tools/libxl/libxl_domain.c b/tools/libxl/libxl_domain.c
index 533bcdf240..3377bba994 100644
--- a/tools/libxl/libxl_domain.c
+++ b/tools/libxl/libxl_domain.c
@@ -1369,6 +1369,12 @@ int libxl_set_vcpuonline(libxl_ctx *ctx, uint32_t domid, libxl_bitmap *cpumap)
     }
 
     maxcpus = libxl_bitmap_count_set(cpumap);
+    if (maxcpus == 0)
+    {
+        LOGED(ERROR, domid, "Requested 0 VCPUs!");
+        rc = ERROR_FAIL;
+        goto out;
+    }
     if (maxcpus > info.vcpu_max_id + 1)
     {
         LOGED(ERROR, domid, "Requested %d VCPUs, however maxcpus is %d!",
diff --git a/tools/xl/xl_vcpu.c b/tools/xl/xl_vcpu.c
index aef486864c..71d3a5c96d 100644
--- a/tools/xl/xl_vcpu.c
+++ b/tools/xl/xl_vcpu.c
@@ -13,6 +13,7 @@
  */
 
 #include <stdlib.h>
+#include <limits.h>
 
 #include <libxl.h>
 #include <libxl_utils.h>
@@ -331,13 +332,14 @@ int main_vcpupin(int argc, char **argv)
 static int vcpuset(uint32_t domid, const char* nr_vcpus, int check_host)
 {
     char *endptr;
-    unsigned int max_vcpus, i;
+    unsigned int i;
+    unsigned long max_vcpus;
     libxl_bitmap cpumap;
     int rc;
 
     libxl_bitmap_init(&cpumap);
     max_vcpus = strtoul(nr_vcpus, &endptr, 10);
-    if (nr_vcpus == endptr) {
+    if (nr_vcpus == endptr || max_vcpus > INT_MAX) {
         fprintf(stderr, "Error: Invalid argument.\n");
         return 1;
     }
@@ -358,7 +360,7 @@ static int vcpuset(uint32_t domid, const char* nr_vcpus, int check_host)
 
         if (max_vcpus > online_vcpus && max_vcpus > host_cpu) {
             fprintf(stderr, "You are overcommmitting! You have %d physical" \
-                    " CPUs and want %d vCPUs! Aborting, use --ignore-host to" \
+                    " CPUs and want %ld vCPUs! Aborting, use --ignore-host to" \
                     " continue\n", host_cpu, max_vcpus);
             return 1;
         }
@@ -375,7 +377,7 @@ static int vcpuset(uint32_t domid, const char* nr_vcpus, int check_host)
     if (rc == ERROR_DOMAIN_NOTFOUND)
         fprintf(stderr, "Domain %u does not exist.\n", domid);
     else if (rc)
-        fprintf(stderr, "libxl_set_vcpuonline failed domid=%u max_vcpus=%d," \
+        fprintf(stderr, "libxl_set_vcpuonline failed domid=%u max_vcpus=%ld," \
                 " rc: %d\n", domid, max_vcpus, rc);
 
     libxl_bitmap_dispose(&cpumap);