diff --git a/src/casting.cpp b/src/casting.cpp
index 9c43c86..dc27e14 100644
--- a/src/casting.cpp
+++ b/src/casting.cpp
@@ -12,12 +12,28 @@ namespace types {
         auto bool_ty = std::shared_ptr<Type>{
             new FundamentalType{ FundamentalTypeKind::Bool } };
 
-        for (auto& source_ty : { int_ty, char_ty, bool_ty }) {
-            for (auto& target_ty : { int_ty, char_ty, bool_ty }) {
-                casts.push_back(CastDefinition{ source_ty, target_ty, false,
-                    [](codegen::Builder& builder, std::shared_ptr<Type> target, llvm::Value* value) {
-                        return builder.builder->CreateSExtOrTrunc(value, target->codegen(builder), "cast");
-                    } });
+        auto numerical_types = { int_ty, char_ty, bool_ty };
+
+        for (auto& source_ty : numerical_types) {
+            for (auto& target_ty : numerical_types) {
+                if (types::types_equal(source_ty, target_ty)) {
+                    casts.push_back(CastDefinition{ source_ty, target_ty, true,
+                        [](codegen::Builder&, std::shared_ptr<Type>, llvm::Value* value) {
+                            return value;
+                        } });
+                }
+                else if (target_ty->is_signed()) {
+                    casts.push_back(CastDefinition{ source_ty, target_ty, false,
+                        [](codegen::Builder& builder, std::shared_ptr<Type> target, llvm::Value* value) {
+                            return builder.builder->CreateSExtOrTrunc(value, target->codegen(builder), "cast");
+                        } });
+                }
+                else {
+                    casts.push_back(CastDefinition{ source_ty, target_ty, false,
+                        [](codegen::Builder& builder, std::shared_ptr<Type> target, llvm::Value* value) {
+                            return builder.builder->CreateZExtOrTrunc(value, target->codegen(builder), "cast");
+                        } });
+                }
             }
         }
 
diff --git a/src/types.cpp b/src/types.cpp
index acca953..e715457 100644
--- a/src/types.cpp
+++ b/src/types.cpp
@@ -75,6 +75,10 @@ namespace types {
         return {};
     }
 
+    bool Type::is_signed() {
+        false;
+    }
+
     std::pair<llvm::Value*, std::shared_ptr<Type>> FundamentalType::load(codegen::Builder&, llvm::Value* ptr) {
         auto self = std::make_shared<FundamentalType>(*this);
         return std::pair(ptr, self);
@@ -124,6 +128,18 @@ namespace types {
         }
     }
 
+    bool FundamentalType::is_signed() {
+        switch (this->m_ty) {
+        case FundamentalTypeKind::Int:
+            return true;
+        case FundamentalTypeKind::Bool:
+        case FundamentalTypeKind::Char:
+            return false;
+        default:
+            throw std::runtime_error("Invalid type");
+        }
+    }
+
     std::string FunctionType::formatted() {
         std::stringstream out{ "" };
         out << "(";
diff --git a/src/types.h b/src/types.h
index 95d3769..0b5bd72 100644
--- a/src/types.h
+++ b/src/types.h
@@ -33,6 +33,7 @@ namespace types {
         virtual llvm::Value* sub(codegen::Builder& builder, llvm::Value* lhs, llvm::Value* rhs);
         virtual llvm::Value* lt(codegen::Builder& builder, llvm::Value* lhs, llvm::Value* rhs);
         virtual llvm::Value* gt(codegen::Builder& builder, llvm::Value* lhs, llvm::Value* rhs);
+        virtual bool is_signed();
     };
 
     class FundamentalType : public Type {
@@ -47,6 +48,7 @@ namespace types {
         virtual llvm::Value* sub(codegen::Builder& builder, llvm::Value* lhs, llvm::Value* rhs) override;
         virtual llvm::Value* lt(codegen::Builder& builder, llvm::Value* lhs, llvm::Value* rhs) override;
         virtual llvm::Value* gt(codegen::Builder& builder, llvm::Value* lhs, llvm::Value* rhs) override;
+        virtual bool is_signed() override;
     };