diff --git a/lib/arm-mes/arm.M1 b/lib/arm-mes/arm.M1
index 9bf19126..384f8776 100644
--- a/lib/arm-mes/arm.M1
+++ b/lib/arm-mes/arm.M1
@@ -1,5 +1,5 @@
 ### GNU Mes --- Maxwell Equations of Software
-### Copyright © 2017,2018,2020 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+### Copyright © 2017,2018,2020,2022 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
 ### Copyright © 2019,2020 Danny Milosavljevic <dannym@scratchpost.org>
 ###
 ### This file is part of GNU Mes.
@@ -91,6 +91,7 @@ DEFINE mov____%r0,(%r1) 000081e5
 DEFINE mov____%r1,%r0 0100a0e1
 DEFINE mov____%r1,%r2 0120a0e1
 DEFINE mov____%esp,%r0 0d00a0e1
+DEFINE mov____%esp,%r3 0d30a0e1
 
 # e59f9004        ldr     r9, [pc, #4]    ; <L1>
 # e5890000        str     r0, [r9]
diff --git a/module/mescc/armv4/as.scm b/module/mescc/armv4/as.scm
index e30338d3..3787c9be 100644
--- a/module/mescc/armv4/as.scm
+++ b/module/mescc/armv4/as.scm
@@ -383,9 +383,9 @@
                `(,(string-append "push___%" r0))
                (armv4:call-label #f "__mesabi_imod" 2))
         ;; __mesabi_uldiv(a, b, remainderp)
-        (append `(("push___%r0") ; slot for remainder
-                  ("mov____%esp,%r0")
-                  ("push___%r0") ; pointer to remainder
+        (append `(("push___%r3")        ; slot for remainder
+                  ("mov____%esp,%r3")
+                  ("push___%r3")        ; pointer to remainder
                   (,(string-append "push___%" r1))
                   (,(string-append "push___%" r0)))
                 (armv4:call-label #f "__mesabi_uldiv" 3)