1 files changed, 7 insertions, 0 deletions
diff --git a/src/ir.cpp b/src/ir.cpp
index 61e296c360..6a63597ed8 100644
--- a/src/ir.cpp
+++ b/src/ir.cpp
@@ -7053,6 +7053,13 @@ static IrInstruction *ir_analyze_widen_or_shorten(IrAnalyze *ira, IrInstruction
         ConstExprValue *val = ir_resolve_const(ira, target, UndefBad);
         if (!val)
             return ira->codegen->invalid_instruction;
+        if (val->data.x_bignum.is_negative && wanted_type->id == TypeTableEntryIdInt &&
+            !wanted_type->data.integral.is_signed)
+        {
+            ir_add_error(ira, source_instr,
+                buf_sprintf("attempt to cast negative value to unsigned integer"));
+            return ira->codegen->invalid_instruction;
+        }
         IrInstruction *result = ir_create_const(&ira->new_irb, source_instr->scope,
                 source_instr->source_node, wanted_type);
         result->value = *val;