diff --git a/readme.md b/readme.md
index a5dbac7a..36312fd9 100644
--- a/readme.md
+++ b/readme.md
@@ -44,7 +44,7 @@ Download the latest release from [the Releases page](https://github.com/Alexandr
 Then, run:
 
 ```sh
-sudo apt install libfftw3-dev libglfw3-dev libvolk2-dev libsoapysdr-dev libairspyhf-dev libiio-dev libad9361-dev librtaudio-dev libhackrf-dev
+sudo apt install libfftw3-dev libglfw3-dev libvolk2-dev libzstd-dev libsoapysdr-dev libairspyhf-dev libiio-dev libad9361-dev librtaudio-dev libhackrf-dev
 sudo dpkg -i sdrpp_debian_amd64.deb
 ```
 
diff --git a/source_modules/hackrf_source/src/main.cpp b/source_modules/hackrf_source/src/main.cpp
index a70fd579..abb4bcc5 100644
--- a/source_modules/hackrf_source/src/main.cpp
+++ b/source_modules/hackrf_source/src/main.cpp
@@ -137,6 +137,10 @@ public:
         hackrf_device_list_t* _devList = hackrf_device_list();
 
         for (int i = 0; i < _devList->devicecount; i++) {
+            // Skip devices that are in use
+            if (_devList->serial_numbers[i] == NULL) { continue; }
+
+            // Save the device serial number
             devList.push_back(_devList->serial_numbers[i]);
             devListTxt += (char*)(_devList->serial_numbers[i] + 16);
             devListTxt += '\0';
diff --git a/source_modules/rtl_sdr_source/src/main.cpp b/source_modules/rtl_sdr_source/src/main.cpp
index de6d5686..dba27610 100644
--- a/source_modules/rtl_sdr_source/src/main.cpp
+++ b/source_modules/rtl_sdr_source/src/main.cpp
@@ -523,8 +523,8 @@ private:
         RTLSDRSourceModule* _this = (RTLSDRSourceModule*)ctx;
         int sampCount = len / 2;
         for (int i = 0; i < sampCount; i++) {
-            _this->stream.writeBuf[i].re = (float)(buf[i * 2] - 127) / 128.0f;
-            _this->stream.writeBuf[i].im = (float)(buf[(i * 2) + 1] - 127) / 128.0f;
+            _this->stream.writeBuf[i].re = ((float)buf[i * 2] - 127.4) / 128.0f;
+            _this->stream.writeBuf[i].im = ((float)buf[(i * 2) + 1] - 127.4) / 128.0f;
         }
         if (!_this->stream.swap(sampCount)) { return; }
     }