diff --git a/include/abstract_data_store.h b/include/abstract_data_store.h
index 2e0266814..976174378 100644
--- a/include/abstract_data_store.h
+++ b/include/abstract_data_store.h
@@ -18,6 +18,8 @@ template <typename data_t> class AbstractDataStore
   public:
     AbstractDataStore(const location_t capacity, const size_t dim);
 
+    // virtual ~AbstractDataStore() = default;
+
     // Return number of points returned
     virtual location_t load(const std::string &filename) = 0;
 
diff --git a/include/logger.h b/include/logger.h
index 1a1b79e71..0b17807db 100644
--- a/include/logger.h
+++ b/include/logger.h
@@ -14,8 +14,13 @@
 
 namespace diskann
 {
+#ifdef ENABLE_CUSTOM_LOGGER
 DISKANN_DLLEXPORT extern std::basic_ostream<char> cout;
 DISKANN_DLLEXPORT extern std::basic_ostream<char> cerr;
+#else
+using std::cerr;
+using std::cout;
+#endif
 
 enum class DISKANN_DLLEXPORT LogLevel
 {
diff --git a/include/logger_impl.h b/include/logger_impl.h
index 510c5aa08..03c65e0ce 100644
--- a/include/logger_impl.h
+++ b/include/logger_impl.h
@@ -11,6 +11,7 @@
 
 namespace diskann
 {
+#ifdef ENABLE_CUSTOM_LOGGER
 class ANNStreamBuf : public std::basic_streambuf<char>
 {
   public:
@@ -36,30 +37,25 @@ class ANNStreamBuf : public std::basic_streambuf<char>
     int flush();
     void logImpl(char *str, int numchars);
 
-// Why the two buffer-sizes? If we are running normally, we are basically
-// interacting with a character output system, so we short-circuit the
-// output process by keeping an empty buffer and writing each character
-// to stdout/stderr. But if we are running in OLS, we have to take all
-// the text that is written to diskann::cout/diskann:cerr, consolidate it
-// and push it out in one-shot, because the OLS infra does not give us
-// character based output. Therefore, we use a larger buffer that is large
-// enough to store the longest message, and continuously add characters
-// to it. When the calling code outputs a std::endl or std::flush, sync()
-// will be called and will output a log level, component name, and the text
-// that has been collected. (sync() is also called if the buffer is full, so
-// overflows/missing text are not a concern).
-// This implies calling code _must_ either print std::endl or std::flush
-// to ensure that the message is written immediately.
-#ifdef ENABLE_CUSTOM_LOGGER
+    // Why the two buffer-sizes? If we are running normally, we are basically
+    // interacting with a character output system, so we short-circuit the
+    // output process by keeping an empty buffer and writing each character
+    // to stdout/stderr. But if we are running in OLS, we have to take all
+    // the text that is written to diskann::cout/diskann:cerr, consolidate it
+    // and push it out in one-shot, because the OLS infra does not give us
+    // character based output. Therefore, we use a larger buffer that is large
+    // enough to store the longest message, and continuously add characters
+    // to it. When the calling code outputs a std::endl or std::flush, sync()
+    // will be called and will output a log level, component name, and the text
+    // that has been collected. (sync() is also called if the buffer is full, so
+    // overflows/missing text are not a concern).
+    // This implies calling code _must_ either print std::endl or std::flush
+    // to ensure that the message is written immediately.
+
     static const int BUFFER_SIZE = 1024;
-#else
-    // Allocating an arbitrarily small buffer here because the overflow() and
-    // other function implementations push the BUFFER_SIZE chars into the
-    // buffer before flushing to fwrite.
-    static const int BUFFER_SIZE = 4;
-#endif
 
     ANNStreamBuf(const ANNStreamBuf &);
     ANNStreamBuf &operator=(const ANNStreamBuf &);
 };
+#endif
 } // namespace diskann
diff --git a/src/logger.cpp b/src/logger.cpp
index dc27f718d..052f54877 100644
--- a/src/logger.cpp
+++ b/src/logger.cpp
@@ -10,13 +10,12 @@
 namespace diskann
 {
 
+#ifdef ENABLE_CUSTOM_LOGGER
 DISKANN_DLLEXPORT ANNStreamBuf coutBuff(stdout);
 DISKANN_DLLEXPORT ANNStreamBuf cerrBuff(stderr);
 
 DISKANN_DLLEXPORT std::basic_ostream<char> cout(&coutBuff);
 DISKANN_DLLEXPORT std::basic_ostream<char> cerr(&cerrBuff);
-
-#ifdef ENABLE_CUSTOM_LOGGER
 std::function<void(LogLevel, const char *)> g_logger;
 
 void SetCustomLogger(std::function<void(LogLevel, const char *)> logger)
@@ -24,7 +23,6 @@ void SetCustomLogger(std::function<void(LogLevel, const char *)> logger)
     g_logger = logger;
     diskann::cout << "Set Custom Logger" << std::endl;
 }
-#endif
 
 ANNStreamBuf::ANNStreamBuf(FILE *fp)
 {
@@ -38,11 +36,7 @@ ANNStreamBuf::ANNStreamBuf(FILE *fp)
     }
     _fp = fp;
     _logLevel = (_fp == stdout) ? LogLevel::LL_Info : LogLevel::LL_Error;
-#ifdef ENABLE_CUSTOM_LOGGER
     _buf = new char[BUFFER_SIZE + 1]; // See comment in the header
-#else
-    _buf = new char[BUFFER_SIZE]; // See comment in the header
-#endif
 
     std::memset(_buf, 0, (BUFFER_SIZE) * sizeof(char));
     setp(_buf, _buf + BUFFER_SIZE - 1);
@@ -88,17 +82,16 @@ int ANNStreamBuf::flush()
 }
 void ANNStreamBuf::logImpl(char *str, int num)
 {
-#ifdef ENABLE_CUSTOM_LOGGER
     str[num] = '\0'; // Safe. See the c'tor.
     // Invoke the OLS custom logging function.
     if (g_logger)
     {
         g_logger(_logLevel, str);
     }
+}
 #else
-    fwrite(str, sizeof(char), num, _fp);
-    fflush(_fp);
+using std::cerr;
+using std::cout;
 #endif
-}
 
 } // namespace diskann