diff --git a/nac3core/src/codegen/expr.rs b/nac3core/src/codegen/expr.rs
index 3300d3c..d5602bc 100644
--- a/nac3core/src/codegen/expr.rs
+++ b/nac3core/src/codegen/expr.rs
@@ -19,6 +19,7 @@ use crate::{
 use inkwell::{
     AddressSpace,
     attributes::{Attribute, AttributeLoc},
+    IntPredicate,
     types::{AnyType, BasicType, BasicTypeEnum},
     values::{BasicValueEnum, FunctionValue, IntValue, PointerValue}
 };
@@ -924,7 +925,7 @@ pub fn gen_comprehension<'ctx, 'a, G: CodeGenerator>(
             let length = ctx.builder.build_int_add(length, int32.const_int(1, false), "add1");
             // in case length is non-positive
             let is_valid =
-                ctx.builder.build_int_compare(inkwell::IntPredicate::SGT, length, zero_32, "check");
+                ctx.builder.build_int_compare(IntPredicate::SGT, length, zero_32, "check");
             let normal = ctx.ctx.append_basic_block(current, "listcomp.normal_list");
             let empty = ctx.ctx.append_basic_block(current, "listcomp.empty_list");
             let list_init = ctx.ctx.append_basic_block(current, "listcomp.list_init");
@@ -964,7 +965,7 @@ pub fn gen_comprehension<'ctx, 'a, G: CodeGenerator>(
 
             ctx.builder.position_at_end(test_bb);
             let sign =
-                ctx.builder.build_int_compare(inkwell::IntPredicate::SGT, step, zero_32, "sign");
+                ctx.builder.build_int_compare(IntPredicate::SGT, step, zero_32, "sign");
             // add and test
             let tmp = ctx.builder.build_int_add(
                 ctx.builder.build_load(i, "i").into_int_value(),
@@ -973,9 +974,9 @@ pub fn gen_comprehension<'ctx, 'a, G: CodeGenerator>(
             );
             ctx.builder.build_store(i, tmp);
             // if step > 0, continue when i < end
-            let cmp1 = ctx.builder.build_int_compare(inkwell::IntPredicate::SLT, tmp, end, "cmp1");
+            let cmp1 = ctx.builder.build_int_compare(IntPredicate::SLT, tmp, end, "cmp1");
             // if step < 0, continue when i > end
-            let cmp2 = ctx.builder.build_int_compare(inkwell::IntPredicate::SGT, tmp, end, "cmp2");
+            let cmp2 = ctx.builder.build_int_compare(IntPredicate::SGT, tmp, end, "cmp2");
             let pos = ctx.builder.build_and(sign, cmp1, "pos");
             let neg = ctx.builder.build_and(ctx.builder.build_not(sign, "inv"), cmp2, "neg");
             ctx.builder.build_conditional_branch(
@@ -1005,7 +1006,7 @@ pub fn gen_comprehension<'ctx, 'a, G: CodeGenerator>(
             let tmp = ctx.builder.build_load(counter, "i").into_int_value();
             let tmp = ctx.builder.build_int_add(tmp, size_t.const_int(1, false), "inc");
             ctx.builder.build_store(counter, tmp);
-            let cmp = ctx.builder.build_int_compare(inkwell::IntPredicate::SLT, tmp, length, "cmp");
+            let cmp = ctx.builder.build_int_compare(IntPredicate::SLT, tmp, length, "cmp");
             ctx.builder.build_conditional_branch(cmp, body_bb, cont_bb);
 
             ctx.builder.position_at_end(body_bb);
@@ -1359,7 +1360,7 @@ pub fn gen_expr<'ctx, 'a, G: CodeGenerator>(
                     ast::Unaryop::Not => ctx
                         .builder
                         .build_int_compare(
-                            inkwell::IntPredicate::EQ,
+                            IntPredicate::EQ,
                             val,
                             val.get_type().const_zero(),
                             "not",
@@ -1392,9 +1393,14 @@ pub fn gen_expr<'ctx, 'a, G: CodeGenerator>(
                 .fold(Ok(None), |prev: Result<Option<_>, String>, (lhs, rhs, op)| {
                     let ty = ctx.unifier.get_representative(lhs.custom.unwrap());
                     let current =
-                        if [ctx.primitives.int32, ctx.primitives.int64, ctx.primitives.bool]
+                        if [ctx.primitives.int32, ctx.primitives.int64, ctx.primitives.uint32, ctx.primitives.uint64, ctx.primitives.bool]
                             .contains(&ty)
                         {
+                            let use_unsigned_ops = [
+                                ctx.primitives.uint32,
+                                ctx.primitives.uint64,
+                            ].contains(&ty);
+
                             let (lhs, rhs) = if let (
                                 BasicValueEnum::IntValue(lhs),
                                 BasicValueEnum::IntValue(rhs),
@@ -1412,15 +1418,34 @@ pub fn gen_expr<'ctx, 'a, G: CodeGenerator>(
                             } else {
                                 unreachable!()
                             };
+
                             let op = match op {
-                                ast::Cmpop::Eq | ast::Cmpop::Is => inkwell::IntPredicate::EQ,
-                                ast::Cmpop::NotEq => inkwell::IntPredicate::NE,
-                                ast::Cmpop::Lt => inkwell::IntPredicate::SLT,
-                                ast::Cmpop::LtE => inkwell::IntPredicate::SLE,
-                                ast::Cmpop::Gt => inkwell::IntPredicate::SGT,
-                                ast::Cmpop::GtE => inkwell::IntPredicate::SGE,
+                                ast::Cmpop::Eq | ast::Cmpop::Is => IntPredicate::EQ,
+                                ast::Cmpop::NotEq => IntPredicate::NE,
+                                _ if ty == ctx.primitives.bool => unreachable!(),
+                                ast::Cmpop::Lt => if use_unsigned_ops {
+                                    IntPredicate::ULT
+                                } else {
+                                    IntPredicate::SLT
+                                },
+                                ast::Cmpop::LtE => if use_unsigned_ops {
+                                    IntPredicate::ULE
+                                } else {
+                                    IntPredicate::SLE
+                                },
+                                ast::Cmpop::Gt => if use_unsigned_ops {
+                                    IntPredicate::UGT
+                                } else {
+                                    IntPredicate::SGT
+                                },
+                                ast::Cmpop::GtE => if use_unsigned_ops {
+                                    IntPredicate::UGE
+                                } else {
+                                    IntPredicate::SGE
+                                },
                                 _ => unreachable!(),
                             };
+
                             ctx.builder.build_int_compare(op, lhs, rhs, "cmp")
                         } else if ty == ctx.primitives.float {
                             let (lhs, rhs) = if let (
@@ -1655,7 +1680,7 @@ pub fn gen_expr<'ctx, 'a, G: CodeGenerator>(
                         ctx.builder
                             .build_select(
                                 ctx.builder.build_int_compare(
-                                    inkwell::IntPredicate::SLT,
+                                    IntPredicate::SLT,
                                     step,
                                     zero,
                                     "is_neg",
@@ -1696,7 +1721,7 @@ pub fn gen_expr<'ctx, 'a, G: CodeGenerator>(
                     );
                     // handle negative index
                     let is_negative = ctx.builder.build_int_compare(
-                        inkwell::IntPredicate::SLT,
+                        IntPredicate::SLT,
                         raw_index,
                         generator.get_size_type(ctx.ctx).const_zero(),
                         "is_neg",
@@ -1709,7 +1734,7 @@ pub fn gen_expr<'ctx, 'a, G: CodeGenerator>(
                     // unsigned less than is enough, because negative index after adjustment is
                     // bigger than the length (for unsigned cmp)
                     let bound_check = ctx.builder.build_int_compare(
-                        inkwell::IntPredicate::ULT,
+                        IntPredicate::ULT,
                         index,
                         len,
                         "inbound",