diff --git a/spec/std/isa/inst/C/c.ld.yaml b/spec/std/isa/inst/C/c.ld.yaml
index b8d67ebc8..9672b0ae7 100644
--- a/spec/std/isa/inst/C/c.ld.yaml
+++ b/spec/std/isa/inst/C/c.ld.yaml
@@ -18,6 +18,7 @@ definedBy:
     - C
     - Zca
     - Zclsd
+base: 32
 assembly: xd, imm(xs1)
 encoding:
   RV32: