diff --git a/src/TypeDef.h b/src/TypeDef.h
index 0d250d50..e2d8c914 100644
--- a/src/TypeDef.h
+++ b/src/TypeDef.h
@@ -218,6 +218,11 @@
 */
 #define RADIOLIB_ERR_INVALID_RSSI_THRESHOLD                    (-27)
 
+/*!
+  \brief A `NULL` pointer has been encountered. If you see this, there may be a potential security vulnerability.
+*/
+#define RADIOLIB_ERR_NULL_POINTER                              (-28)
+
 // RF69-specific status codes
 
 /*!
diff --git a/src/modules/CC1101/CC1101.cpp b/src/modules/CC1101/CC1101.cpp
index 6a5a0f2b..9407523b 100644
--- a/src/modules/CC1101/CC1101.cpp
+++ b/src/modules/CC1101/CC1101.cpp
@@ -89,7 +89,7 @@ int16_t CC1101::begin(float freq, float br, float freqDev, float rxBw, int8_t po
   RADIOLIB_ASSERT(state);
 
   // set default sync word
-  uint8_t sw[2] = RADIOLIB_CC1101_DEFAULT_SW;
+  uint8_t sw[RADIOLIB_CC1101_DEFAULT_SW_LEN] = RADIOLIB_CC1101_DEFAULT_SW;
   state = setSyncWord(sw[0], sw[1], 0, false);
   RADIOLIB_ASSERT(state);
 
@@ -490,9 +490,7 @@ int16_t CC1101::setRxBandwidth(float rxBw) {
       float point = (RADIOLIB_CC1101_CRYSTAL_FREQ * 1000000.0)/(8 * (m + 4) * ((uint32_t)1 << e));
       if(fabs((rxBw * 1000.0) - point) <= 1000) {
         // set Rx channel filter bandwidth
-        uint16_t state = SPIsetRegValue(RADIOLIB_CC1101_REG_MDMCFG4, (e << 6) | (m << 4), 7, 4);
-
-        return(state);
+        return(SPIsetRegValue(RADIOLIB_CC1101_REG_MDMCFG4, (e << 6) | (m << 4), 7, 4));
       }
 
     }
@@ -526,6 +524,10 @@ int16_t CC1101::setFrequencyDeviation(float freqDev) {
 }
 
 int16_t CC1101::getFrequencyDeviation(float *freqDev) {
+  if (freqDev == NULL) {
+    return(RADIOLIB_ERR_NULL_POINTER);
+  }
+
   // if ASK/OOK, deviation makes no sense
   if (_modulation == RADIOLIB_CC1101_MOD_FORMAT_ASK_OOK) {
     *freqDev = 0.0;
@@ -534,7 +536,7 @@ int16_t CC1101::getFrequencyDeviation(float *freqDev) {
   }
 
   // get exponent and mantissa values from registers
-  uint8_t e = (uint8_t)SPIgetRegValue(RADIOLIB_CC1101_REG_DEVIATN, 6, 4);
+  uint8_t e = (uint8_t)(SPIgetRegValue(RADIOLIB_CC1101_REG_DEVIATN, 6, 4) >> 4);
   uint8_t m = (uint8_t)SPIgetRegValue(RADIOLIB_CC1101_REG_DEVIATN, 2, 0);
 
   // calculate frequency deviation (pag. 79 of the CC1101 datasheet):
@@ -682,9 +684,7 @@ int16_t CC1101::setPreambleLength(uint8_t preambleLength) {
       return(RADIOLIB_ERR_INVALID_PREAMBLE_LENGTH);
   }
 
-  uint16_t state = SPIsetRegValue(RADIOLIB_CC1101_REG_MDMCFG1, value, 6, 4);
-
-  return(state);
+  return(SPIsetRegValue(RADIOLIB_CC1101_REG_MDMCFG1, value, 6, 4));
 }
 
 int16_t CC1101::setNodeAddress(uint8_t nodeAddr, uint8_t numBroadcastAddrs) {
diff --git a/src/modules/CC1101/CC1101.h b/src/modules/CC1101/CC1101.h
index 8c2100f2..bb245cbe 100644
--- a/src/modules/CC1101/CC1101.h
+++ b/src/modules/CC1101/CC1101.h
@@ -501,8 +501,8 @@
 
 //Defaults
 #define RADIOLIB_CC1101_DEFAULT_FREQ                           434.0
-#define RADIOLIB_CC1101_DEFAULT_BR                             48.0
-#define RADIOLIB_CC1101_DEFAULT_FREQDEV                        48.0
+#define RADIOLIB_CC1101_DEFAULT_BR                             4.8
+#define RADIOLIB_CC1101_DEFAULT_FREQDEV                        5.0
 #define RADIOLIB_CC1101_DEFAULT_RXBW                           135.0
 #define RADIOLIB_CC1101_DEFAULT_POWER                          10
 #define RADIOLIB_CC1101_DEFAULT_PREAMBLELEN                    16
@@ -536,7 +536,7 @@ class CC1101: public PhysicalLayer {
     /*!
       \brief Initialization method.
 
-      \param freq Carrier frequency in MHz. Defaults to 434.0 MHz.
+      \param freq Carrier frequency in MHz. Defaults to 434 MHz.
 
       \param br Bit rate to be used in kbps. Defaults to 4.8 kbps.
 
@@ -550,7 +550,13 @@ class CC1101: public PhysicalLayer {
 
       \returns \ref status_codes
     */
-    int16_t begin(float freq = 434.0, float br = 4.8, float freqDev = 5.0, float rxBw = 135.0, int8_t power = 10, uint8_t preambleLength = 16);
+    int16_t begin(
+      float freq = RADIOLIB_CC1101_DEFAULT_FREQ,
+      float br = RADIOLIB_CC1101_DEFAULT_BR,
+      float freqDev = RADIOLIB_CC1101_DEFAULT_FREQDEV,
+      float rxBw = RADIOLIB_CC1101_DEFAULT_RXBW,
+      int8_t power = RADIOLIB_CC1101_DEFAULT_POWER,
+      uint8_t preambleLength = RADIOLIB_CC1101_DEFAULT_PREAMBLELEN);
 
     /*!
       \brief Blocking binary transmit method.
@@ -1006,7 +1012,6 @@ class CC1101: public PhysicalLayer {
     bool _crcOn = true;
     bool _directMode = true;
 
-    uint8_t _syncWordLength = RADIOLIB_CC1101_DEFAULT_SW_LEN;
     int8_t _power = RADIOLIB_CC1101_DEFAULT_POWER;
 
 
diff --git a/src/modules/RF69/RF69.cpp b/src/modules/RF69/RF69.cpp
index 5187c54c..5cfd833a 100644
--- a/src/modules/RF69/RF69.cpp
+++ b/src/modules/RF69/RF69.cpp
@@ -59,7 +59,7 @@ int16_t RF69::begin(float freq, float br, float freqDev, float rxBw, int8_t powe
   RADIOLIB_ASSERT(state);
 
   // configure bitrate
-   _rxBw = rxBw;
+  _rxBw = rxBw;
   state = setBitRate(br);
   RADIOLIB_ASSERT(state);
 
@@ -615,7 +615,6 @@ int16_t RF69::setFrequencyDeviation(float freqDev) {
   setMode(RADIOLIB_RF69_STANDBY);
 
   // set frequency deviation from carrier frequency
-  uint32_t base = 1;
   uint32_t fdev = (newFreqDev * (uint32_t(1) << RADIOLIB_RF69_DIV_EXPONENT)) / 32000;
   int16_t state = _mod->SPIsetRegValue(RADIOLIB_RF69_REG_FDEV_MSB, (fdev & 0xFF00) >> 8, 5, 0);
   state |= _mod->SPIsetRegValue(RADIOLIB_RF69_REG_FDEV_LSB, fdev & 0x00FF, 7, 0);
@@ -624,6 +623,10 @@ int16_t RF69::setFrequencyDeviation(float freqDev) {
 }
 
 int16_t RF69::getFrequencyDeviation(float *freqDev) {
+  if (freqDev == NULL) {
+    return(RADIOLIB_ERR_NULL_POINTER);
+  }
+
   if (RF69::_ook) {
     *freqDev = 0.0;
     
@@ -715,9 +718,8 @@ int16_t RF69::setPreambleLength(uint8_t preambleLen) {
 
   uint8_t preLenBytes = preambleLen / 8;
   _mod->SPIwriteRegister(RADIOLIB_RF69_REG_PREAMBLE_MSB, 0x00);
-  uint16_t state = _mod->SPIsetRegValue(RADIOLIB_RF69_REG_PREAMBLE_LSB, preLenBytes);
 
-  return (state);
+  return (_mod->SPIsetRegValue(RADIOLIB_RF69_REG_PREAMBLE_LSB, preLenBytes));
 }
 
 int16_t RF69::setNodeAddress(uint8_t nodeAddr) {
diff --git a/src/modules/RF69/RF69.h b/src/modules/RF69/RF69.h
index 777d8d04..7cb41d90 100644
--- a/src/modules/RF69/RF69.h
+++ b/src/modules/RF69/RF69.h
@@ -464,8 +464,8 @@
 
 // Defaults
 #define RADIOLIB_RF69_DEFAULT_FREQ                             434.0
-#define RADIOLIB_RF69_DEFAULT_BR                               48.0
-#define RADIOLIB_RF69_DEFAULT_FREQDEV                          50.0
+#define RADIOLIB_RF69_DEFAULT_BR                               4.8
+#define RADIOLIB_RF69_DEFAULT_FREQDEV                          5.0
 #define RADIOLIB_RF69_DEFAULT_RXBW                             125.0
 #define RADIOLIB_RF69_DEFAULT_POWER                            10
 #define RADIOLIB_RF69_DEFAULT_PREAMBLELEN                      16
@@ -512,14 +512,14 @@ class RF69: public PhysicalLayer {
 
       \returns \ref status_codes
     */
-    //int16_t begin(float freq = 434.0, float br = 4.8, float freqDev = 5.0, float rxBw = 125.0, int8_t power = 10, uint8_t preambleLen = 16);
       int16_t begin(
-      float freq = RADIOLIB_RF69_DEFAULT_FREQ,
-      float br = RADIOLIB_RF69_DEFAULT_BR,
-      float freqDev = RADIOLIB_RF69_DEFAULT_FREQDEV,
-      float rxBw = RADIOLIB_RF69_DEFAULT_RXBW,
-      int8_t power = RADIOLIB_RF69_DEFAULT_POWER,
-      uint8_t preambleLen = RADIOLIB_RF69_DEFAULT_PREAMBLELEN);
+        float freq = RADIOLIB_RF69_DEFAULT_FREQ,
+        float br = RADIOLIB_RF69_DEFAULT_BR,
+        float freqDev = RADIOLIB_RF69_DEFAULT_FREQDEV,
+        float rxBw = RADIOLIB_RF69_DEFAULT_RXBW,
+        int8_t power = RADIOLIB_RF69_DEFAULT_POWER,
+        uint8_t preambleLen = RADIOLIB_RF69_DEFAULT_PREAMBLELEN);
+
     /*!
       \brief Reset method. Will reset the chip to the default state using RST pin.
     */
diff --git a/src/modules/nRF24/nRF24.cpp b/src/modules/nRF24/nRF24.cpp
index fdc3f6f9..f00f42e3 100644
--- a/src/modules/nRF24/nRF24.cpp
+++ b/src/modules/nRF24/nRF24.cpp
@@ -254,8 +254,7 @@ int16_t nRF24::setFrequency(float freq) {
 
   // set frequency
   uint8_t freqRaw = (uint16_t)freq - 2400;
-  //return(_mod->SPIsetRegValue(RADIOLIB_NRF24_REG_RF_CH, freqRaw, 6, 0));
-  uint16_t state = _mod->SPIsetRegValue(RADIOLIB_NRF24_REG_RF_CH, freqRaw, 6, 0);
+  int16_t state = _mod->SPIsetRegValue(RADIOLIB_NRF24_REG_RF_CH, freqRaw, 6, 0);
 
   if(state == RADIOLIB_ERR_NONE) {
     _freq = freq;
diff --git a/src/modules/nRF24/nRF24.h b/src/modules/nRF24/nRF24.h
index bf3d8b06..72605c6f 100644
--- a/src/modules/nRF24/nRF24.h
+++ b/src/modules/nRF24/nRF24.h
@@ -215,12 +215,12 @@ class nRF24: public PhysicalLayer {
 
       \returns \ref status_codes
     */
-    //int16_t begin(int16_t freq = 2400, int16_t dataRate = 1000, int8_t power = -12, uint8_t addrWidth = 5);
       int16_t begin(
-      int16_t freq = RADIOLIB_NRF24_DEFAULT_FREQ,
-      int16_t dataRate = RADIOLIB_NRF24_DEFAULT_DR,
-      int8_t power = RADIOLIB_NRF24_DEFAULT_POWER,
-      uint8_t addrWidth = RADIOLIB_NRF24_DEFAULT_ADDRWIDTH);
+        int16_t freq = RADIOLIB_NRF24_DEFAULT_FREQ,
+        int16_t dataRate = RADIOLIB_NRF24_DEFAULT_DR,
+        int8_t power = RADIOLIB_NRF24_DEFAULT_POWER,
+        uint8_t addrWidth = RADIOLIB_NRF24_DEFAULT_ADDRWIDTH);
+
     /*!
       \brief Sets the module to sleep mode.
 
@@ -520,7 +520,6 @@ class nRF24: public PhysicalLayer {
   protected:
 #endif
 
-    //uint8_t _addrWidth = 0;
     int16_t _freq = RADIOLIB_NRF24_DEFAULT_FREQ;
     int16_t _dataRate = RADIOLIB_NRF24_DEFAULT_DR;
     int8_t _power = RADIOLIB_NRF24_DEFAULT_POWER;