diff --git a/block/qcow2.c b/block/qcow2.c
index 6f53ec6..7aece65 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1120,16 +1120,19 @@
     int ret, new_l1_size;
 
     if (offset & 511) {
+        error_report("The new size must be a multiple of 512");
         return -EINVAL;
     }
 
     /* cannot proceed if image has snapshots */
     if (s->nb_snapshots) {
+        error_report("Can't resize an image which has snapshots");
         return -ENOTSUP;
     }
 
     /* shrinking is currently not supported */
     if (offset < bs->total_sectors * 512) {
+        error_report("qcow2 doesn't support shrinking images yet");
         return -ENOTSUP;
     }
 
diff --git a/qemu-img.c b/qemu-img.c
index 8df3564..0e48b35 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1614,7 +1614,7 @@
         printf("Image resized.\n");
         break;
     case -ENOTSUP:
-        error_report("This image format does not support resize");
+        error_report("This image does not support resize");
         break;
     case -EACCES:
         error_report("Image is read-only");