diff --git a/lib/cretonne/src/abi.rs b/lib/cretonne/src/abi.rs
index 5c121824aa..05c96c79d5 100644
--- a/lib/cretonne/src/abi.rs
+++ b/lib/cretonne/src/abi.rs
@@ -11,7 +11,7 @@ use std::cmp::Ordering;
 ///
 /// An argument may go through a sequence of legalization steps before it reaches the final
 /// `Assign` action.
-#[derive(Clone, Copy)]
+#[derive(Clone, Copy, Debug)]
 pub enum ArgAction {
     /// Assign the argument to the given location.
     Assign(ArgumentLoc),
diff --git a/lib/cretonne/src/regalloc/affinity.rs b/lib/cretonne/src/regalloc/affinity.rs
index 1c50cbbbab..7d85ae8721 100644
--- a/lib/cretonne/src/regalloc/affinity.rs
+++ b/lib/cretonne/src/regalloc/affinity.rs
@@ -13,7 +13,7 @@ use ir::{AbiParam, ArgumentLoc};
 use isa::{TargetIsa, RegInfo, RegClassIndex, OperandConstraint, ConstraintKind};
 
 /// Preferred register allocation for an SSA value.
-#[derive(Clone, Copy)]
+#[derive(Clone, Copy, Debug)]
 pub enum Affinity {
     /// No affinity.
     ///