diff --git a/0001-data-Fix-issues-on-32-bit.patch b/0001-data-Fix-issues-on-32-bit.patch
new file mode 100644
index 0000000..d8339d0
--- /dev/null
+++ b/0001-data-Fix-issues-on-32-bit.patch
@@ -0,0 +1,62 @@
+From fe6538aafe5f8d6fc6b90ae8f6d3686c711288fd Mon Sep 17 00:00:00 2001
+From: "Richard W.M. Jones" <rjones@redhat.com>
+Date: Mon, 23 Aug 2021 10:34:53 +0100
+Subject: [PATCH] data: Fix issues on 32 bit
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Commit 9352ad00e3 ("data: New functions new_node/get_node with simpler
+usage") added a new expr() function to let you construct expressions.
+However it uses varargs so callers have to be strict about the types
+of the parameters, and the compiler cannot verify this.
+
+When creating EXPR_FILL the parameters are uint8_t, uint64_t, where
+varargs always promotes uint8_t to int.  We called it in a few places
+with incorrect types.  The error showed up when compiling on i686, but
+actually we were very lucky this did not manifest on 64 bit platforms
+too.  It only worked because of how x86-64 ABI passes some arguments
+in registers so that int is passed in a 64 bit register.  On a 64 bit
+platform that uses the stack it could have failed.
+
+Use casts as appropriate.  Strongly typed qualified unions à la OCaml
+would help here!
+
+Fixes: commit 9352ad00e3e1fff679f4eabb2208bfa1e1443a29
+---
+ plugins/data/format.c | 6 +++---
+ 1 file changed, 3 insertions(+), 3 deletions(-)
+
+diff --git a/plugins/data/format.c b/plugins/data/format.c
+index f1b4219e..60b73ef9 100644
+--- a/plugins/data/format.c
++++ b/plugins/data/format.c
+@@ -1358,14 +1358,14 @@ optimize_ast (node_id root, node_id *root_rtn)
+      */
+     if (get_node (root).string.size > 1) {
+       const string s = get_node (root).string;
+-      uint64_t b = s.ptr[0];
++      uint8_t b = s.ptr[0];
+ 
+       for (i = 1; i < s.size; ++i)
+         if (s.ptr[i] != b)
+           break;
+ 
+       if (i == s.size) {
+-        *root_rtn = new_node (expr (EXPR_FILL, b, s.size));
++        *root_rtn = new_node (expr (EXPR_FILL, b, (uint64_t) s.size));
+         return 0;
+       }
+     }
+@@ -1485,7 +1485,7 @@ exprs_can_combine (expr_t e0, expr_t e1, node_id *id_rtn)
+     switch (e1.t) {
+     case EXPR_BYTE:             /* byte byte => fill | string */
+       if (e0.b == e1.b) {
+-        *id_rtn = new_node (expr (EXPR_FILL, e0.b, 2));
++        *id_rtn = new_node (expr (EXPR_FILL, e0.b, UINT64_C(2)));
+       }
+       else {
+         if (string_append (&s, e0.b) == -1 ||
+-- 
+2.32.0
+
diff --git a/nbdkit.spec b/nbdkit.spec
index f7286f8..460661d 100644
--- a/nbdkit.spec
+++ b/nbdkit.spec
@@ -72,6 +72,9 @@ Source2:        libguestfs.keyring
 # Maintainer script which helps with handling patches.
 Source3:        copy-patches.sh
 
+# Fix issues in nbdkit-data-plugin on 32 bit platforms.
+Patch1:         0001-data-Fix-issues-on-32-bit.patch
+
 BuildRequires: make
 %if 0%{patches_touch_autotools}
 BuildRequires:  autoconf, automake, libtool