diff --git a/src/compiler/crystal/codegen/debug.cr b/src/compiler/crystal/codegen/debug.cr
index e296839b3dba..ba7a0444fdb3 100644
--- a/src/compiler/crystal/codegen/debug.cr
+++ b/src/compiler/crystal/codegen/debug.cr
@@ -64,7 +64,7 @@ module Crystal
     end
 
     def create_debug_type(type : FloatType)
-      di_builder.create_basic_type(type.to_s, type.bytes * 8, type.bytes * 8, LLVM::DwarfTypeEncoding::Float)
+      di_builder.create_basic_type(type.to_s, 8u64 * type.bytes, 8u64 * type.bytes, LLVM::DwarfTypeEncoding::Float)
     end
 
     def create_debug_type(type : BoolType)
@@ -98,9 +98,9 @@ module Crystal
 
       ivars.each_with_index do |(name, ivar), idx|
         if (ivar_type = ivar.type?) && (ivar_debug_type = get_debug_type(ivar_type))
-          offset = @program.target_machine.data_layout.offset_of_element(struct_type, idx + (type.struct? ? 0 : 1))
+          offset = @program.target_machine.data_layout.offset_of_element(struct_type, idx &+ (type.struct? ? 0 : 1))
           size = @program.target_machine.data_layout.size_in_bits(llvm_embedded_type(ivar_type))
-          member = di_builder.create_member_type(nil, name[1..-1], nil, 1, size, size, offset * 8, LLVM::DIFlags::Zero, ivar_debug_type)
+          member = di_builder.create_member_type(nil, name[1..-1], nil, 1, size, size, 8u64 * offset, LLVM::DIFlags::Zero, ivar_debug_type)
           element_types << member
         end
       end
@@ -108,7 +108,7 @@ module Crystal
       size = @program.target_machine.data_layout.size_in_bits(struct_type)
       debug_type = di_builder.create_struct_type(nil, type.to_s, nil, 1, size, size, LLVM::DIFlags::Zero, nil, di_builder.get_or_create_type_array(element_types))
       unless type.struct?
-        debug_type = di_builder.create_pointer_type(debug_type, llvm_typer.pointer_size * 8, llvm_typer.pointer_size * 8, type.to_s)
+        debug_type = di_builder.create_pointer_type(debug_type, 8u64 * llvm_typer.pointer_size, 8u64 * llvm_typer.pointer_size, type.to_s)
       end
       di_builder.replace_temporary(tmp_debug_type, debug_type)
       debug_type
@@ -117,7 +117,7 @@ module Crystal
     def create_debug_type(type : PointerInstanceType)
       element_type = get_debug_type(type.element_type)
       return unless element_type
-      di_builder.create_pointer_type(element_type, llvm_typer.pointer_size * 8, llvm_typer.pointer_size * 8, type.to_s)
+      di_builder.create_pointer_type(element_type, 8u64 * llvm_typer.pointer_size, 8u64 * llvm_typer.pointer_size, type.to_s)
     end
 
     def create_debug_type(type : StaticArrayInstanceType)
diff --git a/src/llvm/lib_llvm.cr b/src/llvm/lib_llvm.cr
index c072a17fd635..a4846f76cb13 100644
--- a/src/llvm/lib_llvm.cr
+++ b/src/llvm/lib_llvm.cr
@@ -196,7 +196,7 @@ lib LibLLVM
   fun is_constant = LLVMIsConstant(val : ValueRef) : Int32
   fun is_function_var_arg = LLVMIsFunctionVarArg(ty : TypeRef) : Int32
   fun module_create_with_name_in_context = LLVMModuleCreateWithNameInContext(module_id : UInt8*, context : ContextRef) : ModuleRef
-  fun offset_of_element = LLVMOffsetOfElement(td : TargetDataRef, struct_type : TypeRef, element : LibC::UInt) : Int64
+  fun offset_of_element = LLVMOffsetOfElement(td : TargetDataRef, struct_type : TypeRef, element : LibC::UInt) : UInt64
   fun pass_manager_builder_create = LLVMPassManagerBuilderCreate : PassManagerBuilderRef
   fun pass_manager_builder_set_opt_level = LLVMPassManagerBuilderSetOptLevel(builder : PassManagerBuilderRef, opt_level : UInt32)
   fun pass_manager_builder_set_size_level = LLVMPassManagerBuilderSetSizeLevel(builder : PassManagerBuilderRef, size_level : UInt32)