diff --git a/src/NimBLEAttValue.h b/src/NimBLEAttValue.h
index bddf020e..56ceae46 100644
--- a/src/NimBLEAttValue.h
+++ b/src/NimBLEAttValue.h
@@ -21,8 +21,13 @@
 #include "syscfg/syscfg.h"
 #if CONFIG_BT_NIMBLE_ENABLED
 
-# ifdef NIMBLE_CPP_ARDUINO_STRING_AVAILABLE
-#  include <Arduino.h>
+/* Enables the use of Arduino String class for attribute values */
+# ifndef NIMBLE_CPP_ARDUINO_STRING_AVAILABLE
+#  define NIMBLE_CPP_ARDUINO_STRING_AVAILABLE (__has_include(<Arduino.h>))
+# endif
+
+# if NIMBLE_CPP_ARDUINO_STRING_AVAILABLE
+#  include <WString.h>
 # endif
 
 # include <string>
@@ -145,7 +150,7 @@ class NimBLEAttValue {
     NimBLEAttValue(const std::vector<uint8_t> vec, uint16_t max_len = BLE_ATT_ATTR_MAX_LEN)
         : NimBLEAttValue(&vec[0], vec.size(), max_len) {}
 
-# ifdef NIMBLE_CPP_ARDUINO_STRING_AVAILABLE
+# if NIMBLE_CPP_ARDUINO_STRING_AVAILABLE
     /**
      * @brief Construct with an initial value from an Arduino String.
      * @param str An Arduino String containing to the initial value to set.
@@ -398,7 +403,7 @@ class NimBLEAttValue {
     /** @brief Inequality operator */
     bool operator!=(const NimBLEAttValue& source) const { return !(*this == source); }
 
-# ifdef NIMBLE_CPP_ARDUINO_STRING_AVAILABLE
+# if NIMBLE_CPP_ARDUINO_STRING_AVAILABLE
     /** @brief Operator; Get the value as an Arduino String value. */
     operator String() const { return String(reinterpret_cast<char*>(m_attr_value)); }
 # endif
diff --git a/src/NimBLEStream.h b/src/NimBLEStream.h
index b5ba6d80..28d3d467 100644
--- a/src/NimBLEStream.h
+++ b/src/NimBLEStream.h
@@ -31,6 +31,10 @@
 # include <type_traits>
 # include <cstdarg>
 
+# ifndef NIMBLE_CPP_ARDUINO_STRING_AVAILABLE
+#  define NIMBLE_CPP_ARDUINO_STRING_AVAILABLE (__has_include(<Arduino.h>))
+# endif
+
 # if NIMBLE_CPP_ARDUINO_STRING_AVAILABLE
 #  include <Stream.h>
 # else
@@ -100,7 +104,7 @@ class NimBLEStream : public Stream {
      */
     void setRxOverflowCallback(RxOverflowCallback cb, void* userArg = nullptr) {
         m_rxOverflowCallback = cb;
-        m_rxOverflowUserArg = userArg;
+        m_rxOverflowUserArg  = userArg;
     }
 
     operator bool() const { return ready(); }
@@ -118,17 +122,17 @@ class NimBLEStream : public Stream {
     static void  txDrainEventCb(struct ble_npl_event* ev);
     static void  txDrainCalloutCb(struct ble_npl_event* ev);
 
-    ByteRingBuffer*        m_txBuf{nullptr};
-    ByteRingBuffer*        m_rxBuf{nullptr};
-    uint8_t                m_txChunkBuf[MYNEWT_VAL(BLE_ATT_PREFERRED_MTU)];
-    uint32_t               m_txBufSize{1024};
-    uint32_t               m_rxBufSize{1024};
-    ble_npl_event          m_txDrainEvent{};
-    ble_npl_callout        m_txDrainCallout{};
+    ByteRingBuffer*    m_txBuf{nullptr};
+    ByteRingBuffer*    m_rxBuf{nullptr};
+    uint8_t            m_txChunkBuf[MYNEWT_VAL(BLE_ATT_PREFERRED_MTU)];
+    uint32_t           m_txBufSize{1024};
+    uint32_t           m_rxBufSize{1024};
+    ble_npl_event      m_txDrainEvent{};
+    ble_npl_callout    m_txDrainCallout{};
     RxOverflowCallback m_rxOverflowCallback{nullptr};
-    void*                  m_rxOverflowUserArg{nullptr};
-    bool                   m_coInitialized{false};
-    bool                   m_eventInitialized{false};
+    void*              m_rxOverflowUserArg{nullptr};
+    bool               m_coInitialized{false};
+    bool               m_eventInitialized{false};
 };
 
 # if MYNEWT_VAL(BLE_ROLE_PERIPHERAL)
@@ -203,13 +207,13 @@ class NimBLEStreamClient : public NimBLEStream {
 
     // Attach a discovered remote characteristic; app owns discovery/connection.
     // Set subscribeNotify=true to receive notifications into RX buffer.
-    bool begin(NimBLERemoteCharacteristic* pChr,
-               bool                        subscribeNotify = false,
-               uint32_t                    txBufSize       = 1024,
-               uint32_t                    rxBufSize       = 1024);
-    void end() override;
-    void setNotifyCallback(NimBLERemoteCharacteristic::notify_callback cb) { m_userNotifyCallback = cb; }
-    bool ready() const override;
+    bool         begin(NimBLERemoteCharacteristic* pChr,
+                       bool                        subscribeNotify = false,
+                       uint32_t                    txBufSize       = 1024,
+                       uint32_t                    rxBufSize       = 1024);
+    void         end() override;
+    void         setNotifyCallback(NimBLERemoteCharacteristic::notify_callback cb) { m_userNotifyCallback = cb; }
+    bool         ready() const override;
     virtual void flush() override;
 
     using NimBLEStream::write; // Inherit template write overloads