diff --git a/src/nouveau/compiler/nak/sm20.rs b/src/nouveau/compiler/nak/sm20.rs
index b320f26b432..2a0ebcabc76 100644
--- a/src/nouveau/compiler/nak/sm20.rs
+++ b/src/nouveau/compiler/nak/sm20.rs
@@ -148,7 +148,9 @@ enum AluSrc {
 impl AluSrc {
     fn from_src(src: Option<&Src>) -> AluSrc {
         if let Some(src) = src {
-            assert!(src.src_swizzle.is_none());
+            assert!(
+                src.src_swizzle.is_none() || src.src_swizzle == SrcSwizzle::Yy
+            );
             // do not assert src_mod, can be encoded by opcode.
 
             match &src.src_ref {
@@ -299,7 +301,7 @@ impl SM20Encoder<'_> {
     }
 
     fn set_reg_src(&mut self, range: Range<usize>, src: &Src) {
-        assert!(src.src_swizzle.is_none());
+        assert!(src.src_swizzle.is_none() || src.src_swizzle == SrcSwizzle::Yy);
         self.set_reg_src_ref(range, &src.src_ref);
     }
 
diff --git a/src/nouveau/compiler/nak/sm32.rs b/src/nouveau/compiler/nak/sm32.rs
index a9d64dad849..04f0d4f8f27 100644
--- a/src/nouveau/compiler/nak/sm32.rs
+++ b/src/nouveau/compiler/nak/sm32.rs
@@ -230,7 +230,7 @@ impl SM32Encoder<'_> {
     }
 
     fn set_reg_src(&mut self, range: Range<usize>, src: &Src) {
-        assert!(src.src_swizzle.is_none());
+        assert!(src.src_swizzle.is_none() || src.src_swizzle == SrcSwizzle::Yy);
         self.set_reg_src_ref(range, &src.src_ref);
     }
 
@@ -319,7 +319,7 @@ enum AluSrc {
 
 impl AluSrc {
     fn from_src(src: &Src) -> AluSrc {
-        assert!(src.src_swizzle.is_none());
+        assert!(src.src_swizzle.is_none() || src.src_swizzle == SrcSwizzle::Yy);
         // do not assert src_mod, can be encoded by opcode.
 
         match &src.src_ref {