diff --git a/block/io.c b/block/io.c
index e404627..3846e2e 100644
--- a/block/io.c
+++ b/block/io.c
@@ -3056,7 +3056,8 @@
                                   int64_t bytes)
 {
     BdrvTrackedRequest req;
-    int max_pdiscard, ret;
+    int ret;
+    int64_t max_pdiscard;
     int head, tail, align;
     BlockDriverState *bs = child->bs;
 
diff --git a/include/block/block_int.h b/include/block/block_int.h
index d518703..9b4e074 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -674,11 +674,12 @@
      * otherwise. */
     uint32_t request_alignment;
 
-    /* Maximum number of bytes that can be discarded at once (since it
-     * is signed, it must be < 2G, if set). Must be multiple of
-     * pdiscard_alignment, but need not be power of 2. May be 0 if no
-     * inherent 32-bit limit */
-    int32_t max_pdiscard;
+    /*
+     * Maximum number of bytes that can be discarded at once. Must be multiple
+     * of pdiscard_alignment, but need not be power of 2. May be 0 if no
+     * inherent 64-bit limit.
+     */
+    int64_t max_pdiscard;
 
     /* Optimal alignment for discard requests in bytes. A power of 2
      * is best but not mandatory.  Must be a multiple of