diff --git a/src/compiler/nir/nir_lower_mediump.c b/src/compiler/nir/nir_lower_mediump.c
index 1c8df13dd0d..c0289dd0f91 100644
--- a/src/compiler/nir/nir_lower_mediump.c
+++ b/src/compiler/nir/nir_lower_mediump.c
@@ -742,14 +742,15 @@ can_opt_16bit_src(nir_def *ssa, nir_alu_type src_type, bool sext_matters)
             can_opt &= (const_is_u16(comp) || const_is_i16(comp));
       } else if (nir_scalar_is_alu(comp)) {
          nir_alu_instr *alu = nir_instr_as_alu(comp.def->parent_instr);
-         if (alu->src[0].src.ssa->bit_size != 16)
-            return false;
+         bool is_16bit = alu->src[0].src.ssa->bit_size == 16;
 
-         if (alu->op == nir_op_f2f32)
+         if ((alu->op == nir_op_f2f32 && is_16bit) ||
+             alu->op == nir_op_unpack_half_2x16_split_x ||
+             alu->op == nir_op_unpack_half_2x16_split_y)
             can_opt &= opt_f16;
-         else if (alu->op == nir_op_i2i32)
+         else if (alu->op == nir_op_i2i32 && is_16bit)
             can_opt &= opt_i16 || opt_i16_u16;
-         else if (alu->op == nir_op_u2u32)
+         else if (alu->op == nir_op_u2u32 && is_16bit)
             can_opt &= opt_u16 || opt_i16_u16;
          else
             return false;
@@ -782,6 +783,23 @@ opt_16bit_src(nir_builder *b, nir_instr *instr, nir_src *src, nir_alu_type src_t
       } else {
          /* conversion instruction */
          new_comps[i] = nir_scalar_chase_alu_src(comp, 0);
+         if (new_comps[i].def->bit_size != 16) {
+            assert(new_comps[i].def->bit_size == 32);
+
+            nir_def *extract = nir_channel(b, new_comps[i].def, new_comps[i].comp);
+            switch (nir_scalar_alu_op(comp)) {
+            case nir_op_unpack_half_2x16_split_x:
+               extract = nir_unpack_32_2x16_split_x(b, extract);
+               break;
+            case nir_op_unpack_half_2x16_split_y:
+               extract = nir_unpack_32_2x16_split_y(b, extract);
+               break;
+            default:
+               unreachable("unsupported alu op");
+            }
+
+            new_comps[i] = nir_get_scalar(extract, 0);
+         }
       }
    }