diff --git a/tools/libxc/xc_foreign_memory.c b/tools/libxc/xc_foreign_memory.c
index 7dfc8172e7..43abf01a83 100644
--- a/tools/libxc/xc_foreign_memory.c
+++ b/tools/libxc/xc_foreign_memory.c
@@ -27,7 +27,7 @@ void *xc_map_foreign_pages(xc_interface *xch, uint32_t dom, int prot,
     int i, *err;
 
     if (num < 0) {
-        errno = -EINVAL;
+        errno = EINVAL;
         return NULL;
     }
 
diff --git a/tools/libxc/xc_mem_paging.c b/tools/libxc/xc_mem_paging.c
index 269cbddebe..8aa7d4d34d 100644
--- a/tools/libxc/xc_mem_paging.c
+++ b/tools/libxc/xc_mem_paging.c
@@ -76,7 +76,7 @@ int xc_mem_paging_load(xc_interface *xch, domid_t domain_id,
 {
     int rc, old_errno;
 
-    errno = -EINVAL;
+    errno = EINVAL;
 
     if ( !buffer )
         return -1;
diff --git a/tools/libxc/xc_minios.c b/tools/libxc/xc_minios.c
index a48f0de7b1..e621417cf3 100644
--- a/tools/libxc/xc_minios.c
+++ b/tools/libxc/xc_minios.c
@@ -349,7 +349,7 @@ static int minios_evtchn_unbind(xc_evtchn *xce, xc_osdep_handle h, evtchn_port_t
         }
     }
     printf("Warning: couldn't find port %"PRId32" for xc handle %x\n", port, fd);
-    errno = -EINVAL;
+    errno = EINVAL;
     return -1;
 }