diff --git a/include/hwinfo/battery.h b/include/hwinfo/battery.h
index cad9db7f..84434195 100644
--- a/include/hwinfo/battery.h
+++ b/include/hwinfo/battery.h
@@ -18,10 +18,10 @@ class Battery {
   explicit Battery(int8_t id = 0);
   ~Battery() = default;
 
-  std::string vendor();
-  std::string model();
-  std::string serialNumber();
-  std::string technology();
+  std::string& vendor();
+  std::string& model();
+  std::string& serialNumber();
+  std::string& technology();
   uint32_t energyFull();
 
   double capacity();
diff --git a/include/hwinfo/cpu.h b/include/hwinfo/cpu.h
index 5a575ba3..b1b4aafe 100644
--- a/include/hwinfo/cpu.h
+++ b/include/hwinfo/cpu.h
@@ -24,8 +24,8 @@ struct Jiffies {
     working = _working;
   }
 
-  int64_t working{-1};
-  int64_t all{-1};
+  int64_t working;
+  int64_t all;
 };
 #endif
 
diff --git a/include/hwinfo/cpuid.h b/include/hwinfo/cpuid.h
index 35d2af08..f351594a 100644
--- a/include/hwinfo/cpuid.h
+++ b/include/hwinfo/cpuid.h
@@ -3,8 +3,6 @@
 
 #pragma once
 
-#include <cstdint>
-
 #include "hwinfo/platform.h"
 
 #if defined(HWINFO_X86)
diff --git a/include/hwinfo/gpu.h b/include/hwinfo/gpu.h
index edc796b2..80588770 100644
--- a/include/hwinfo/gpu.h
+++ b/include/hwinfo/gpu.h
@@ -17,9 +17,9 @@ class GPU {
  public:
   ~GPU() = default;
 
-  HWI_NODISCARD std::string vendor() const;
-  HWI_NODISCARD std::string name() const;
-  HWI_NODISCARD std::string driverVersion() const;
+  HWI_NODISCARD const std::string& vendor() const;
+  HWI_NODISCARD const std::string& name() const;
+  HWI_NODISCARD const std::string& driverVersion() const;
   HWI_NODISCARD int64_t memory_Bytes() const;
   HWI_NODISCARD int64_t frequency_MHz() const;
   HWI_NODISCARD int num_cores() const;
diff --git a/include/hwinfo/mainboard.h b/include/hwinfo/mainboard.h
index 215d30a4..f1ae7069 100644
--- a/include/hwinfo/mainboard.h
+++ b/include/hwinfo/mainboard.h
@@ -17,10 +17,10 @@ class MainBoard {
   MainBoard();
   ~MainBoard() = default;
 
-  std::string vendor() const;
-  std::string name() const;
-  std::string version() const;
-  std::string serialNumber() const;
+  const std::string& vendor() const;
+  const std::string& name() const;
+  const std::string& version() const;
+  const std::string& serialNumber() const;
 
  private:
   std::string _vendor;
diff --git a/src/battery.cpp b/src/battery.cpp
index 54e5bb2b..fea560bc 100644
--- a/src/battery.cpp
+++ b/src/battery.cpp
@@ -10,7 +10,7 @@ namespace hwinfo {
 Battery::Battery(int8_t id) { _id = id; }
 
 // _____________________________________________________________________________________________________________________
-std::string Battery::vendor() {
+std::string& Battery::vendor() {
   if (_vendor.empty()) {
     _vendor = getVendor();
   }
@@ -18,7 +18,7 @@ std::string Battery::vendor() {
 }
 
 // _____________________________________________________________________________________________________________________
-std::string Battery::model() {
+std::string& Battery::model() {
   if (_model.empty()) {
     _model = getModel();
   }
@@ -26,7 +26,7 @@ std::string Battery::model() {
 }
 
 // _____________________________________________________________________________________________________________________
-std::string Battery::serialNumber() {
+std::string& Battery::serialNumber() {
   if (_serialNumber.empty()) {
     _serialNumber = getSerialNumber();
   }
@@ -34,7 +34,7 @@ std::string Battery::serialNumber() {
 }
 
 // _____________________________________________________________________________________________________________________
-std::string Battery::technology() {
+std::string& Battery::technology() {
   if (_technology.empty()) {
     _technology = getTechnology();
   }
diff --git a/src/gpu.cpp b/src/gpu.cpp
index 20cbd912..fe9cd7fb 100644
--- a/src/gpu.cpp
+++ b/src/gpu.cpp
@@ -8,13 +8,13 @@
 namespace hwinfo {
 
 // _____________________________________________________________________________________________________________________
-std::string GPU::vendor() const { return _vendor; }
+const std::string& GPU::vendor() const { return _vendor; }
 
-// ____________________________________________________________________________________________________________________
-std::string GPU::name() const { return _name; }
+// _____________________________________________________________________________________________________________________
+const std::string& GPU::name() const { return _name; }
 
-// ____________________________________________________________________________________________________________________
-std::string GPU::driverVersion() const { return _driverVersion; }
+// _____________________________________________________________________________________________________________________
+const std::string& GPU::driverVersion() const { return _driverVersion; }
 
 // _____________________________________________________________________________________________________________________
 int GPU::id() const { return _id; }
diff --git a/src/mainboard.cpp b/src/mainboard.cpp
index ec068469..50fac714 100644
--- a/src/mainboard.cpp
+++ b/src/mainboard.cpp
@@ -6,15 +6,15 @@
 namespace hwinfo {
 
 // _____________________________________________________________________________________________________________________
-std::string MainBoard::vendor() const { return _vendor; }
+const std::string& MainBoard::vendor() const { return _vendor; }
 
 // _____________________________________________________________________________________________________________________
-std::string MainBoard::name() const { return _name; }
+const std::string& MainBoard::name() const { return _name; }
 
 // _____________________________________________________________________________________________________________________
-std::string MainBoard::version() const { return _version; }
+const std::string& MainBoard::version() const { return _version; }
 
 // _____________________________________________________________________________________________________________________
-std::string MainBoard::serialNumber() const { return _serialNumber; }
+const std::string& MainBoard::serialNumber() const { return _serialNumber; }
 
 }  // namespace hwinfo
\ No newline at end of file