diff --git a/lib/utils_device.c b/lib/utils_device.c
index bd481e8a..3bd37cc7 100644
--- a/lib/utils_device.c
+++ b/lib/utils_device.c
@@ -773,10 +773,10 @@ static int device_internal_prepare(struct crypt_device *cd, struct device *devic
 		return -ENOTSUP;
 	}
 
-	log_dbg(cd, "Allocating a free loop device.");
+	log_dbg(cd, "Allocating a free loop device (block size: %zu).", SECTOR_SIZE);
 
 	/* Keep the loop open, detached on last close. */
-	loop_fd = crypt_loop_attach(&loop_device, device->path, 0, 1, &readonly);
+	loop_fd = crypt_loop_attach(&loop_device, device->path, 0, 1, &readonly, SECTOR_SIZE);
 	if (loop_fd == -1) {
 		log_err(cd, _("Attaching loopback device failed "
 			"(loop device with autoclear flag is required)."));
@@ -795,6 +795,8 @@ static int device_internal_prepare(struct crypt_device *cd, struct device *devic
 		return r;
 	}
 
+	log_dbg(cd, "Attached loop device block size is %zu bytes.", device_block_size_fd(loop_fd, NULL));
+
 	device->loop_fd = loop_fd;
 	device->file_path = file_path;
 	device->init_done = 1;
diff --git a/lib/utils_loop.c b/lib/utils_loop.c
index efda3858..c712f1c5 100644
--- a/lib/utils_loop.c
+++ b/lib/utils_loop.c
@@ -35,6 +35,7 @@
 #include <linux/loop.h>
 
 #include "utils_loop.h"
+#include "libcryptsetup_macros.h"
 
 #define LOOP_DEV_MAJOR 7
 
@@ -50,6 +51,10 @@
 #define LOOP_SET_CAPACITY 0x4C07
 #endif
 
+#ifndef LOOP_SET_BLOCK_SIZE
+#define LOOP_SET_BLOCK_SIZE 0x4C09
+#endif
+
 #ifndef LOOP_CONFIGURE
 #define LOOP_CONFIGURE 0x4C0A
 struct loop_config {
@@ -111,7 +116,7 @@ static char *crypt_loop_get_device(void)
 }
 
 int crypt_loop_attach(char **loop, const char *file, int offset,
-		      int autoclear, int *readonly)
+		      int autoclear, int *readonly, size_t blocksize)
 {
 	struct loop_config config = {0};
 	char *lo_file_name;
@@ -136,8 +141,10 @@ int crypt_loop_attach(char **loop, const char *file, int offset,
 	config.info.lo_offset = offset;
 	if (autoclear)
 		config.info.lo_flags |= LO_FLAGS_AUTOCLEAR;
+	if (blocksize > SECTOR_SIZE)
+		config.block_size = blocksize;
 
-	while (loop_fd < 0)  {
+	while (loop_fd < 0) {
 		*loop = crypt_loop_get_device();
 		if (!*loop)
 			goto out;
@@ -167,9 +174,8 @@ int crypt_loop_attach(char **loop, const char *file, int offset,
 		}
 	}
 
-	if (fallback)
-	{
-		while (loop_fd < 0)  {
+	if (fallback) {
+		while (loop_fd < 0) {
 			*loop = crypt_loop_get_device();
 			if (!*loop)
 				goto out;
@@ -188,6 +194,9 @@ int crypt_loop_attach(char **loop, const char *file, int offset,
 			}
 		}
 
+		if (blocksize > SECTOR_SIZE)
+			(void)ioctl(loop_fd, LOOP_SET_BLOCK_SIZE, (unsigned long)blocksize);
+
 		if (ioctl(loop_fd, LOOP_SET_STATUS64, &config.info) < 0) {
 			(void)ioctl(loop_fd, LOOP_CLR_FD, 0);
 			goto out;
diff --git a/lib/utils_loop.h b/lib/utils_loop.h
index cc445d42..b3f87bd4 100644
--- a/lib/utils_loop.h
+++ b/lib/utils_loop.h
@@ -27,7 +27,7 @@
 char *crypt_loop_backing_file(const char *loop);
 int crypt_loop_device(const char *loop);
 int crypt_loop_attach(char **loop, const char *file, int offset,
-		      int autoclear, int *readonly);
+		      int autoclear, int *readonly, size_t blocksize);
 int crypt_loop_detach(const char *loop);
 int crypt_loop_resize(const char *loop);