diff --git a/src/nouveau/compiler/nak/to_cssa.rs b/src/nouveau/compiler/nak/to_cssa.rs
index 2e01a9dae2a..5caffc1df68 100644
--- a/src/nouveau/compiler/nak/to_cssa.rs
+++ b/src/nouveau/compiler/nak/to_cssa.rs
@@ -355,31 +355,34 @@ impl Function {
                             debug_assert!(src.src_mod.is_none());
                             if let SrcRef::SSA(vec) = &src.src_ref {
                                 debug_assert!(vec.comps() == 1);
-                                let ss = cg.ssa_set(&vec[0]);
-                                if cg.sets_interfere(ps, ss, &self.blocks) {
-                                    let tmp = self.ssa_alloc.alloc(file);
-                                    pcopy.push(tmp.into(), *src);
-                                    *src = tmp.into();
-                                } else {
-                                    cg.sets_merge(ps, ss);
+                                if vec[0].file() == file {
+                                    let ss = cg.ssa_set(&vec[0]);
+                                    if cg.sets_interfere(ps, ss, &self.blocks) {
+                                        let tmp = self.ssa_alloc.alloc(file);
+                                        pcopy.push(tmp.into(), *src);
+                                        *src = tmp.into();
+                                    } else {
+                                        cg.sets_merge(ps, ss);
+                                    }
+                                    continue;
                                 }
-                            } else {
-                                // Non-SSA sources get an actual Mov instruction
-                                // and are not considered part of the parallel
-                                // copy.
-                                let tmp = self.ssa_alloc.alloc(file);
-                                if DEBUG.annotate() {
-                                    instrs.push(Instr::new_boxed(OpAnnotate {
-                                        annotation: "generated by to_cssa"
-                                            .into(),
-                                    }));
-                                }
-                                instrs.push(Instr::new_boxed(OpCopy {
-                                    dst: tmp.into(),
-                                    src: *src,
-                                }));
-                                *src = tmp.into();
                             }
+
+                            // Non-SSA sources or sources with a different file
+                            // from the destination get an actual copy
+                            // instruction and are not considered part of the
+                            // parallel copy.
+                            let tmp = self.ssa_alloc.alloc(file);
+                            if DEBUG.annotate() {
+                                instrs.push(Instr::new_boxed(OpAnnotate {
+                                    annotation: "generated by to_cssa".into(),
+                                }));
+                            }
+                            instrs.push(Instr::new_boxed(OpCopy {
+                                dst: tmp.into(),
+                                src: *src,
+                            }));
+                            *src = tmp.into();
                         }
 
                         if !pcopy.is_empty() {