diff --git a/src/gallium/drivers/radeonsi/si_shader_nir.c b/src/gallium/drivers/radeonsi/si_shader_nir.c
index beeaa9adb21..135f8711a38 100644
--- a/src/gallium/drivers/radeonsi/si_shader_nir.c
+++ b/src/gallium/drivers/radeonsi/si_shader_nir.c
@@ -48,8 +48,15 @@ static uint8_t si_vectorize_callback(const nir_instr *instr, const void *data)
       return 0;
 
    nir_alu_instr *alu = nir_instr_as_alu(instr);
-   if (nir_dest_bit_size(alu->dest.dest) == 16)
-      return 2;
+   if (nir_dest_bit_size(alu->dest.dest) == 16) {
+      switch (alu->op) {
+      case nir_op_unpack_32_2x16_split_x:
+      case nir_op_unpack_32_2x16_split_y:
+         return 1;
+      default:
+         return 2;
+      }
+   }
 
    return 1;
 }