diff --git a/BasiliskII/src/Unix/video_vosf.h b/BasiliskII/src/Unix/video_vosf.h
index 22bceca9..ae63a698 100644
--- a/BasiliskII/src/Unix/video_vosf.h
+++ b/BasiliskII/src/Unix/video_vosf.h
@@ -181,8 +181,8 @@ static bool video_vosf_init(void)
 	// The "2" more bytes requested are a safety net to insure the
 	// loops in the update routines will terminate.
 	// See "How can we deal with array overrun conditions ?" hereunder for further details.
-	mainBuffer.dirtyPages = (char *) vm_acquire(mainBuffer.pageCount + 2);
-	if (mainBuffer.dirtyPages == VM_MAP_FAILED)
+	mainBuffer.dirtyPages = (char *) malloc(mainBuffer.pageCount + 2);
+	if (mainBuffer.dirtyPages == NULL)
 		return false;
 		
 	PFLAG_CLEAR_ALL;
@@ -190,8 +190,8 @@ static bool video_vosf_init(void)
 	PFLAG_SET(mainBuffer.pageCount+1);
 	
 	// Allocate and fill in pageInfo with start and end (inclusive) row in number of bytes
-	mainBuffer.pageInfo = (ScreenPageInfo *) vm_acquire(mainBuffer.pageCount * sizeof(ScreenPageInfo));
-	if (mainBuffer.pageInfo == VM_MAP_FAILED)
+	mainBuffer.pageInfo = (ScreenPageInfo *) malloc(mainBuffer.pageCount * sizeof(ScreenPageInfo));
+	if (mainBuffer.pageInfo == NULL)
 		return false;
 	
 	uint32 a = 0;
@@ -232,13 +232,13 @@ static bool video_vosf_init(void)
 
 static void video_vosf_exit(void)
 {
-	if (mainBuffer.pageInfo != VM_MAP_FAILED) {
-		vm_release(mainBuffer.pageInfo, mainBuffer.pageCount * sizeof(ScreenPageInfo));
-		mainBuffer.pageInfo = (ScreenPageInfo *) VM_MAP_FAILED;
+	if (mainBuffer.pageInfo) {
+		free(mainBuffer.pageInfo);
+		mainBuffer.pageInfo = NULL;
 	}
-	if (mainBuffer.dirtyPages != VM_MAP_FAILED) {
-		vm_release(mainBuffer.dirtyPages, mainBuffer.pageCount + 2);
-		mainBuffer.dirtyPages = (char *) VM_MAP_FAILED;
+	if (mainBuffer.dirtyPages) {
+		free(mainBuffer.dirtyPages);
+		mainBuffer.dirtyPages = NULL;
 	}
 }
 
diff --git a/BasiliskII/src/Unix/video_x.cpp b/BasiliskII/src/Unix/video_x.cpp
index 07078a82..5fe46010 100644
--- a/BasiliskII/src/Unix/video_x.cpp
+++ b/BasiliskII/src/Unix/video_x.cpp
@@ -523,16 +523,17 @@ driver_base::~driver_base()
 	}
 #ifdef ENABLE_VOSF
 	else {
+		// the_buffer shall always be mapped through vm_acquire() so that we can vm_protect() it at will
+		if (the_buffer != VM_MAP_FAILED) {
+			D(bug(" releasing the_buffer at %p (%d bytes)\n", the_buffer, the_buffer_size));
+			vm_release(the_buffer, the_buffer_size);
+			the_buffer = NULL;
+		}
 		if (the_host_buffer) {
 			D(bug(" freeing the_host_buffer at %p\n", the_host_buffer));
 			free(the_host_buffer);
 			the_host_buffer = NULL;
 		}
-		if (the_buffer) {
-			D(bug(" freeing the_buffer at %p\n", the_buffer));
-			free(the_buffer);
-			the_buffer = NULL;
-		}
 		if (the_buffer_copy) {
 			D(bug(" freeing the_buffer_copy at %p\n", the_buffer_copy));
 			free(the_buffer_copy);
@@ -583,7 +584,7 @@ driver_window::driver_window(const video_mode &mode)
 	// Set absolute mouse mode
 	ADBSetRelMouseMode(mouse_grabbed);
 
-	// Create window (setting backround_pixel, border_pixel and colormap is
+	// Create window (setting background_pixel, border_pixel and colormap is
 	// mandatory when using a non-default visual; in 1-bit mode we use the
 	// default visual, so we can also use the default colormap)
 	XSetWindowAttributes wattr;
@@ -675,8 +676,8 @@ driver_window::driver_window(const video_mode &mode)
 	// Allocate memory for frame buffer (SIZE is extended to page-boundary)
 	the_host_buffer = the_buffer_copy;
 	the_buffer_size = page_extend((aligned_height + 2) * img->bytes_per_line);
-	the_buffer_copy = (uint8 *)vm_acquire(the_buffer_size);
 	the_buffer = (uint8 *)vm_acquire(the_buffer_size);
+	the_buffer_copy = (uint8 *)malloc(the_buffer_size);
 	D(bug("the_buffer = %p, the_buffer_copy = %p, the_host_buffer = %p\n", the_buffer, the_buffer_copy, the_host_buffer));
 #else
 	// Allocate memory for frame buffer
@@ -725,21 +726,6 @@ driver_window::~driver_window()
 		the_buffer_copy = NULL; // don't free() in driver_base dtor
 #endif
 	}
-#ifdef ENABLE_VOSF
-	if (use_vosf) {
-		// don't free() memory mapped buffers in driver_base dtor
-		if (the_buffer != VM_MAP_FAILED) {
-			D(bug(" releasing the_buffer at %p\n", the_buffer));
-			vm_release(the_buffer, the_buffer_size);
-			the_buffer = NULL;
-		}
-		if (the_buffer_copy != VM_MAP_FAILED) {
-			D(bug(" releasing the_buffer_copy at %p\n", the_buffer_copy));
-			vm_release(the_buffer_copy, the_buffer_size);
-			the_buffer_copy = NULL;
-		}
-	}
-#endif
 	if (img) {
 		if (!have_shm)
 			img->data = NULL;
@@ -1086,7 +1072,7 @@ driver_fbdev::driver_fbdev(const video_mode &mode)
 	  // Allocate memory for frame buffer (SIZE is extended to page-boundary)
 	  the_host_buffer = the_buffer;
 	  the_buffer_size = page_extend((height + 2) * bytes_per_row);
-	  the_buffer_copy = (uint8 *)vm_acquire(the_buffer_size);
+	  the_buffer_copy = (uint8 *)malloc(the_buffer_size);
 	  the_buffer = (uint8 *)vm_acquire(the_buffer_size);
 	}
 #else
@@ -1121,14 +1107,6 @@ driver_fbdev::~driver_fbdev()
 			munmap(the_host_buffer, the_buffer_size);
 			the_host_buffer = NULL;
 		}
-		if (the_buffer_copy != VM_MAP_FAILED) {
-			vm_release(the_buffer_copy, the_buffer_size);
-			the_buffer_copy = NULL;
-		}
-		if (the_buffer != VM_MAP_FAILED) {
-			vm_release(the_buffer, the_buffer_size);
-			the_buffer = NULL;
-		}
 	}
 #endif
 }
@@ -1227,7 +1205,7 @@ driver_xf86dga::driver_xf86dga(const video_mode &mode)
 	  // Allocate memory for frame buffer (SIZE is extended to page-boundary)
 	  the_host_buffer = the_buffer;
 	  the_buffer_size = page_extend((height + 2) * bytes_per_row);
-	  the_buffer_copy = (uint8 *)vm_acquire(the_buffer_size);
+	  the_buffer_copy = (uint8 *)malloc(the_buffer_size);
 	  the_buffer = (uint8 *)vm_acquire(the_buffer_size);
 	}
 #else
@@ -1256,15 +1234,6 @@ driver_xf86dga::~driver_xf86dga()
 	else {
 		// don't free() the screen buffer in driver_base dtor
 		the_host_buffer = NULL;
-		
-		if (the_buffer_copy != VM_MAP_FAILED) {
-			vm_release(the_buffer_copy, the_buffer_size);
-			the_buffer_copy = NULL;
-		}
-		if (the_buffer != VM_MAP_FAILED) {
-			vm_release(the_buffer, the_buffer_size);
-			the_buffer = NULL;
-		}
 	}
 #endif
 #ifdef ENABLE_XF86_VIDMODE
diff --git a/BasiliskII/src/Unix/vm_alloc.cpp b/BasiliskII/src/Unix/vm_alloc.cpp
index db19aa7f..e5222963 100644
--- a/BasiliskII/src/Unix/vm_alloc.cpp
+++ b/BasiliskII/src/Unix/vm_alloc.cpp
@@ -162,17 +162,18 @@ int vm_release(void * addr, size_t size)
 		return 0;
 
 #ifdef HAVE_MACH_VM
-	int ret_code = vm_deallocate(mach_task_self(), (vm_address_t)addr, size);
-	return ret_code == KERN_SUCCESS ? 0 : -1;
+	if (vm_deallocate(mach_task_self(), (vm_address_t)addr, size) != KERN_SUCCESS)
+		return -1;
 #else
 #ifdef HAVE_MMAP_VM
-	int ret_code = munmap(addr, size);
-	return ret_code == 0 ? 0 : -1;
+	if (munmap(addr, size) != 0)
+		return -1;
 #else
 	free(addr);
+#endif
+#endif
+	
 	return 0;
-#endif
-#endif
 }
 
 /* Change the memory protection of the region starting at ADDR and