diff --git a/src/vol/namei_ops.c b/src/vol/namei_ops.c
index 9e28fbc1c0..2d6f1ce51d 100644
--- a/src/vol/namei_ops.c
+++ b/src/vol/namei_ops.c
@@ -2742,7 +2742,7 @@ convertVolumeInfo(FD_t fdr, FD_t fdw, afs_uint32 vid)
     struct VolumeDiskData vd;
     char *p;
 
-    if (OS_READ(fdr, (char *)&vd, sizeof(struct VolumeDiskData)) !=
+    if (OS_READ(fdr, &vd, sizeof(struct VolumeDiskData)) !=
 	sizeof(struct VolumeDiskData)) {
 	Log("1 convertVolumeInfo: read failed for %lu with code %d\n",
 	    afs_printable_uint32_lu(vid),
@@ -2761,7 +2761,7 @@ convertVolumeInfo(FD_t fdr, FD_t fdw, afs_uint32 vid)
     if (p && !strcmp(p, ".readonly")) {
 	memset(p, 0, 9);
     }
-    if (OS_WRITE(fdw, (char *)&vd, sizeof(struct VolumeDiskData)) !=
+    if (OS_WRITE(fdw, &vd, sizeof(struct VolumeDiskData)) !=
 	sizeof(struct VolumeDiskData)) {
 	Log("1 convertVolumeInfo: write failed for %lu with code %d\n",
 	    afs_printable_uint32_lu(vid),
diff --git a/src/vol/ntops.c b/src/vol/ntops.c
index 6931fb132a..715480d5ee 100644
--- a/src/vol/ntops.c
+++ b/src/vol/ntops.c
@@ -76,7 +76,7 @@ nt_unlink(char *name)
  *	the handle or -1 on error.
  */
 FD_t
-nt_open(char *name, int flags, int mode)
+nt_open(const char *name, int flags, int mode)
 {
     HANDLE fh;
     DWORD nt_access = 0;
@@ -141,12 +141,12 @@ nt_close(FD_t fd)
 }
 
 int
-nt_write(FD_t fd, char *buf, afs_sfsize_t size)
+nt_write(FD_t fd, void *buf, afs_sfsize_t size)
 {
     BOOL code;
     DWORD nbytes;
 
-    code = WriteFile((HANDLE) fd, (void *)buf, (DWORD) size, &nbytes, NULL);
+    code = WriteFile((HANDLE) fd, buf, (DWORD) size, &nbytes, NULL);
 
     if (!code) {
 	errno = nterr_nt2unix(GetLastError(), EBADF);
@@ -181,12 +181,12 @@ nt_pwrite(FD_t fd, const void * buf, afs_sfsize_t count, afs_foff_t offset)
 }
 
 int
-nt_read(FD_t fd, char *buf, afs_sfsize_t size)
+nt_read(FD_t fd, void *buf, afs_sfsize_t size)
 {
     BOOL code;
     DWORD nbytes;
 
-    code = ReadFile((HANDLE) fd, (void *)buf, (DWORD) size, &nbytes, NULL);
+    code = ReadFile((HANDLE) fd, buf, (DWORD) size, &nbytes, NULL);
 
     if (!code) {
         DWORD gle = GetLastError();
diff --git a/src/vol/ntops.h b/src/vol/ntops.h
index e19dfd61dd..6661979106 100644
--- a/src/vol/ntops.h
+++ b/src/vol/ntops.h
@@ -22,10 +22,10 @@ extern char *PrintInode(char *, Inode);
 #endif
 
 /* Basic file operations */
-extern FD_t nt_open(char *name, int flags, int mode);
+extern FD_t nt_open(const char *name, int flags, int mode);
 extern int nt_close(FD_t fd);
-extern int nt_write(FD_t fd, char *buf, afs_sfsize_t size);
-extern int nt_read(FD_t fd, char *buf, afs_sfsize_t size);
+extern int nt_write(FD_t fd, void *buf, afs_sfsize_t size);
+extern int nt_read(FD_t fd, void *buf, afs_sfsize_t size);
 extern int nt_pread(FD_t fd, void * buf, afs_sfsize_t count, afs_foff_t offset);
 extern int nt_pwrite(FD_t fd, const void * buf, afs_sfsize_t count, afs_foff_t offset);
 extern afs_sfsize_t nt_size(FD_t fd);