diff --git a/src/asahi/compiler/agx_register_allocate.c b/src/asahi/compiler/agx_register_allocate.c
index c226137efb8..4cc1726affd 100644
--- a/src/asahi/compiler/agx_register_allocate.c
+++ b/src/asahi/compiler/agx_register_allocate.c
@@ -61,6 +61,24 @@ agx_write_registers(agx_instr *I, unsigned d)
    }
 }
 
+static inline enum agx_size
+agx_split_width(const agx_instr *I)
+{
+   enum agx_size width = ~0;
+
+   agx_foreach_dest(I, d) {
+      if (agx_is_null(I->dest[d]))
+         continue;
+      else if (width != ~0)
+         assert(width == I->dest[d].size);
+      else
+         width = I->dest[d].size;
+   }
+
+   assert(width != ~0 && "should have been DCE'd");
+   return width;
+}
+
 static unsigned
 agx_assign_regs(BITSET_WORD *used_regs, unsigned count, unsigned align, unsigned max)
 {
@@ -114,7 +132,7 @@ agx_ra_assign_local(agx_block *block, uint8_t *ssa_to_reg, uint8_t *ncomps)
       if (I->op == AGX_OPCODE_P_SPLIT && I->src[0].kill) {
          unsigned reg = ssa_to_reg[I->src[0].value];
          unsigned length = ncomps[I->src[0].value];
-         unsigned width = agx_size_align_16(I->src[0].size);
+         unsigned width = agx_size_align_16(agx_split_width(I));
          unsigned count = length / width;
 
          agx_foreach_dest(I, d) {
@@ -339,7 +357,7 @@ agx_ra(agx_context *ctx)
          continue;
       } else if (ins->op == AGX_OPCODE_P_SPLIT) {
          unsigned base = agx_index_to_reg(ssa_to_reg, ins->src[0]);
-         unsigned width = agx_size_align_16(ins->src[0].size);
+         unsigned width = agx_size_align_16(agx_split_width(ins));
 
          struct agx_copy copies[4];
          unsigned n = 0;
@@ -347,7 +365,6 @@ agx_ra(agx_context *ctx)
          /* Move the sources */
          for (unsigned i = 0; i < 4; ++i) {
             if (agx_is_null(ins->dest[i])) continue;
-            assert(ins->dest[i].size == ins->src[0].size);
 
             copies[n++] = (struct agx_copy) {
                .dest = agx_index_to_reg(ssa_to_reg, ins->dest[i]),