diff --git a/src/glsl/nir/nir_validate.c b/src/glsl/nir/nir_validate.c
index f6a55ccabd5..0a015e43bba 100644
--- a/src/glsl/nir/nir_validate.c
+++ b/src/glsl/nir/nir_validate.c
@@ -460,9 +460,22 @@ validate_phi_src(nir_phi_instr *instr, nir_block *pred, validate_state *state)
 {
    state->instr = &instr->instr;
 
+   assert(instr->dest.is_ssa);
+
    exec_list_validate(&instr->srcs);
    foreach_list_typed(nir_phi_src, src, node, &instr->srcs) {
       if (src->pred == pred) {
+         unsigned num_components;
+         if (src->src.is_ssa)
+            num_components = src->src.ssa->num_components;
+         else {
+            if (src->src.reg.reg->is_packed)
+               num_components = 4; /* can't check anything */
+            else
+               num_components = src->src.reg.reg->num_components;
+         }
+         assert(num_components == instr->dest.ssa.num_components);
+
          validate_src(&src->src, state);
          return;
       }