diff --git a/docs/history.txt b/docs/history.txt
index 9318f9d..e640cba 100644
--- a/docs/history.txt
+++ b/docs/history.txt
@@ -380,6 +380,8 @@
           - update to include all CONFIG.SYS options (except ANYDOS)
         * boot.asm
           - use static read buffer to avoid crossing 64KB boundary
+        * main.c
+          - treat block devices returning 0 units as load failure
         * oemboot.asm - add [optional] PC/MS DOS compatible boot sector
         * sys.c
           - incorporate changes from/for DR-DOS enhancement project
diff --git a/kernel/config.c b/kernel/config.c
index 48ea048..a2f6cd4 100644
--- a/kernel/config.c
+++ b/kernel/config.c
@@ -1444,8 +1444,8 @@ STATIC BOOL LoadDevice(PCStr p, VFP top, int mode)
     {
       struct dhdr FAR *dhp = MK_PTR(struct dhdr, base, next);
       /* init_device returns FALSE on SUCCESS, TRUE otherwise */
-      if ((ret = init_device(dhp, szBuf, mode, &top)))
-        break;
+      ret = init_device(dhp, szBuf, mode, &top);
+      if (ret) break;
 
       next = FP_OFF(dhp->dh_next);
 
diff --git a/sys/sys.c b/sys/sys.c
index dfa5b60..c6ca0b7 100644
--- a/sys/sys.c
+++ b/sys/sys.c
@@ -987,7 +987,7 @@ void correct_bpb(struct bootsectortype *default_bpb,
 }
 
 /* reads in boot sector (1st SEC_SIZE bytes) from file */
-void readBS(const char *bsFile, BYTE *bootsector)
+void readBS(const char *bsFile, UBYTE *bootsector)
 {
   if (bsFile != NULL)
   {
@@ -1018,7 +1018,7 @@ void readBS(const char *bsFile, BYTE *bootsector)
 /* write bs in bsFile to drive's boot record unmodified */
 void restoreBS(const char *bsFile, int drive)
 {
-  unsigned char bootsector[SEC_SIZE];
+  UBYTE bootsector[SEC_SIZE];
 
   if (bsFile == NULL)
   {
@@ -1047,7 +1047,7 @@ void restoreBS(const char *bsFile, int drive)
 }
 
 /* write bootsector to file bsFile */
-void saveBS(const char *bsFile, BYTE *bootsector)
+void saveBS(const char *bsFile, UBYTE *bootsector)
 {
   if (bsFile != NULL)
   {