diff --git a/crates/prometeu-compiler/src/frontends/pbs/lowering.rs b/crates/prometeu-compiler/src/frontends/pbs/lowering.rs
index 36540b40..32645baa 100644
--- a/crates/prometeu-compiler/src/frontends/pbs/lowering.rs
+++ b/crates/prometeu-compiler/src/frontends/pbs/lowering.rs
@@ -601,6 +601,9 @@ impl<'a> Lowerer<'a> {
                                     let rgb565 = (r5 << 11) | (g6 << 5) | b5;
                                     self.emit(Instr::PushBounded(rgb565 as u32));
                                     return Ok(());
+                                } else {
+                                    self.error("E_LOWER_UNSUPPORTED", "Color.rgb only supports literal arguments in this version".to_string(), n.span);
+                                    return Err(());
                                 }
                             }
                         }