diff --git a/Makefile b/Makefile
index 115f71c..a5009f6 100644
--- a/Makefile
+++ b/Makefile
@@ -10,8 +10,6 @@ FLTO   ?= 0
 FPGO   ?= 0
 STRIP  ?= 0
 CPU    ?= 0
-MARCH  ?= 0
-MTUNE  ?= 0
 THREAD ?= 1
 
 # ---------------------------------------------------------------------------
@@ -29,18 +27,18 @@ CONFIG =
 LDFLGS = -lpthread
 CFLAGS = -I$(SUBDIR_LIB)/include -std=gnu99 -Wall
 
-ifneq ($(CPU),0)
+ifneq (,$(firstword $(filter 32 64,$(CPU))))
   CFLAGS += -m$(firstword $(CPU))
 endif
-ifneq ($(TARGET),)
+ifneq (,$(firstword $(TARGET)))
   CFLAGS += --target=$(firstword $(TARGET))
   LDFLGS += --target=$(firstword $(TARGET))
 endif
 
-ifneq ($(MARCH),0)
+ifneq (,$(firstword $(MARCH)))
   CFLAGS += -march=$(firstword $(MARCH))
 endif
-ifneq ($(MTUNE),0)
+ifneq (,$(firstword $(MTUNE)))
   CFLAGS += -mtune=$(firstword $(MTUNE))
 endif
 
@@ -65,7 +63,7 @@ endif
 
 MACHINE := $(shell $(CC) -dumpmachine || echo unknown)
 
-ifeq ($(MACHINE),$(filter %mingw32 %-windows-gnu %-cygwin %-cygnus,$(MACHINE)))
+ifneq (,$(firstword $(filter %mingw32 %-windows-gnu %-cygwin %-cygnus,$(MACHINE))))
   SUFFIX := .exe
 else
   SUFFIX :=
@@ -83,7 +81,7 @@ ifeq ($(STATIC),1)
   LDFLGS += -static
 endif
 
-ifeq ($(MACHINE),$(filter %-w64-mingw32 %w64-windows-gnu,$(MACHINE)))
+ifneq (,$(firstword $(filter %-w64-mingw32 %w64-windows-gnu,$(MACHINE))))
   LDFLGS += -mconsole -municode
 endif
 
diff --git a/libslunkcrypt/src/junk.c b/libslunkcrypt/src/junk.c
index 34b0b42..310916a 100644
--- a/libslunkcrypt/src/junk.c
+++ b/libslunkcrypt/src/junk.c
@@ -40,24 +40,31 @@ static INLINE size_t MIN_SIZE(const size_t a, const size_t b) { return (a > b) ?
 #  include <pthread.h>
 #endif
 
-/* detect destructor support */
-#undef ATTRIB_DESTRUCTOR
+/* detect compiler destructor support */
+#undef HAVE_ATTRIB_DESTRUCTOR
 #if defined(__GNUC__) || defined(__clang__)
-#  define ATTRIB_DESTRUCTOR __attribute__((destructor))
+#  define HAVE_ATTRIB_DESTRUCTOR 1
 #endif
 
-/* detect getentropy() support */
-#undef GETENTROPY
-#if (defined(__linux__) && (__linux__ >= 1)) || (defined(__FreeBSD__) && (__FreeBSD__ >= 12)) || (defined(__OpenBSD__) && (__OpenBSD__ >= 1))
-#  define GETENTROPY getentropy
+/* detect getentropy() or RtlGenRandom() support */
+#undef HAVE_GETENTROPY
+#undef HAVE_WIN32RTLGENRANDOM
+#if defined(_WIN32)
+#  define HAVE_WIN32RTLGENRANDOM 1
+#elif (defined(__linux__) && !defined(__UCLIBC__)) || (defined(__FreeBSD__) && (__FreeBSD__ >= 12)) || defined(__OpenBSD__) || (defined(__sun) && defined(__SVR4))
+#  define HAVE_GETENTROPY 1
+#else
+#  pragma message("Function getentropy() is *not* available -> using fallback!")
 #endif
 
-/* detect explicit_bzero() support */
+/* detect explicit_bzero() or SecureZeroMemory() support */
 #undef EXPLICIT_BZERO
-#if defined(_WIN32) && (_WIN32 >= 1) && defined(SecureZeroMemory)
+#if defined(_WIN32) && defined(SecureZeroMemory)
 #  define EXPLICIT_BZERO SecureZeroMemory
-#elif (defined(__linux__) && (__linux__ >= 1)) || (defined(__FreeBSD__) && (__FreeBSD__ >= 11)) || (defined(__OpenBSD__) && (__OpenBSD__ >= 1))
+#elif (defined(__linux__) && !defined(__UCLIBC__)) || (defined(__FreeBSD__) && (__FreeBSD__ >= 11)) || defined(__OpenBSD__) || (defined(__sun) && defined(__SVR4))
 #  define EXPLICIT_BZERO explicit_bzero
+#else
+#  pragma message("Function explicit_bzero() is *not* available -> using fallback!")
 #endif
 
 // ==========================================================================
@@ -102,15 +109,15 @@ static void exit_random_source(void)
 /* Initialize CSRNG */
 static void init_random_source(void)
 {
-#ifdef _WIN32
+#ifdef HAVE_WIN32RTLGENRANDOM
 	if ((s_advapi32 = LoadLibraryW(L"advapi32.dll")))
 	{
 		s_genrandom = (ptr_genrandom_t) GetProcAddress(s_advapi32, "SystemFunction036");
 	}
 #else
-#if defined(GETENTROPY)
+#if defined(HAVE_GETENTROPY)
 	uint8_t temp;
-	if (GETENTROPY(&temp, sizeof(uint8_t)) >= 0)
+	if (getentropy(&temp, sizeof(uint8_t)) >= 0)
 	{
 		goto init_completed;
 	}
@@ -124,7 +131,7 @@ static void init_random_source(void)
 	}
 init_completed: ;
 #endif
-#if !defined(ATTRIB_DESTRUCTOR)
+#if !defined(HAVE_ATTRIB_DESTRUCTOR)
 	atexit(exit_random_source);
 #endif
 }
@@ -134,7 +141,7 @@ size_t slunkcrypt_random_bytes(uint8_t *const buffer, const size_t length)
 {
 	size_t offset;
 	pthread_once(&s_random_is_initialized, init_random_source);
-#ifdef _WIN32
+#ifdef HAVE_WIN32RTLGENRANDOM
 	if (s_genrandom)
 	{
 		ULONG count;
@@ -162,14 +169,14 @@ size_t slunkcrypt_random_bytes(uint8_t *const buffer, const size_t length)
 		}
 		return offset;
 	}
-#if defined(GETENTROPY)
+#if defined(HAVE_GETENTROPY)
 	else
 	{
 		size_t count;
 		for (offset = 0U; offset < length; offset += count)
 		{
 			count = MIN_SIZE(length - offset, 256U); /*the maximum permitted value is 256*/
-			if (GETENTROPY(buffer + offset, count) < 0)
+			if (getentropy(buffer + offset, count) < 0)
 			{
 				break; /*failed*/
 			}
@@ -206,8 +213,8 @@ void slunkcrypt_bzero(void* const buffer, const size_t length)
 // Destructor
 // ==========================================================================
 
-#if defined(ATTRIB_DESTRUCTOR)
-ATTRIB_DESTRUCTOR void slunkcrypt_destructor()
+#if defined(HAVE_ATTRIB_DESTRUCTOR)
+__attribute__((destructor)) void slunkcrypt_destructor()
 {
 	exit_random_source();
 }