diff --git a/src/nouveau/compiler/nak_encode_sm75.rs b/src/nouveau/compiler/nak_encode_sm75.rs
index 551254636f9..323e800fded 100644
--- a/src/nouveau/compiler/nak_encode_sm75.rs
+++ b/src/nouveau/compiler/nak_encode_sm75.rs
@@ -1140,6 +1140,7 @@ impl SM75Instr {
     fn set_mem_order(&mut self, order: &MemOrder) {
         if self.sm < 80 {
             let scope = match order {
+                MemOrder::Constant => MemScope::System,
                 MemOrder::Weak => MemScope::CTA,
                 MemOrder::Strong(s) => *s,
             };
@@ -1155,7 +1156,7 @@ impl SM75Instr {
             self.set_field(
                 79..81,
                 match order {
-                    /* Constant => 0_u8, */
+                    MemOrder::Constant => 0_u8,
                     MemOrder::Weak => 1_u8,
                     MemOrder::Strong(_) => 2_u8,
                     /* MMIO => 3_u8, */
@@ -1165,6 +1166,7 @@ impl SM75Instr {
             self.set_field(
                 77..81,
                 match order {
+                    MemOrder::Constant => 0x4_u8,
                     MemOrder::Weak => 0x0_u8,
                     MemOrder::Strong(MemScope::CTA) => 0x5_u8,
                     MemOrder::Strong(MemScope::GPU) => 0x7_u8,
diff --git a/src/nouveau/compiler/nak_ir.rs b/src/nouveau/compiler/nak_ir.rs
index c8beb84507a..234b45f2a30 100644
--- a/src/nouveau/compiler/nak_ir.rs
+++ b/src/nouveau/compiler/nak_ir.rs
@@ -1748,6 +1748,7 @@ impl fmt::Display for MemType {
 #[allow(dead_code)]
 #[derive(Clone, Copy, Eq, Hash, PartialEq)]
 pub enum MemOrder {
+    Constant,
     Weak,
     Strong(MemScope),
 }
@@ -1755,6 +1756,7 @@ pub enum MemOrder {
 impl fmt::Display for MemOrder {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
+            MemOrder::Constant => write!(f, "CONSTANT"),
             MemOrder::Weak => write!(f, "WEAK"),
             MemOrder::Strong(scope) => write!(f, "STRONG.{}", scope),
         }