diff --git a/bootfiles/18c/sparc-boot1.lisp b/bootfiles/18c/sparc-boot1.lisp
new file mode 100644
index 0000000000000000000000000000000000000000..699818088d2035be613026cd86fb9fe10bea2f67
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+++ b/bootfiles/18c/sparc-boot1.lisp
@@ -0,0 +1,9 @@
+(in-package "VM")
+(defconstant fixnum-tag-bits (1- lowtag-bits)
+  "Number of tag bits used for a fixnum")
+
+(defconstant fixnum-tag-mask (1- (ash 1 fixnum-tag-bits))
+  "Mask to get the fixnum tag")
+
+(defconstant positive-fixnum-bits (- word-bits fixnum-tag-bits 1)
+  "Maximum number of bits in a positive fixnum")