diff --git a/src/disk.c b/src/disk.c
index 0070843a..4baa8f43 100644
--- a/src/disk.c
+++ b/src/disk.c
@@ -777,10 +777,6 @@ void disk6_init(void) {
     disk6.ddrw = 0;
 }
 
-static volatile int get_errno() {
-    return errno;
-}
-
 const char *disk6_eject(int drive) {
 
 #if !TESTING
@@ -805,7 +801,7 @@ const char *disk6_eject(int drive) {
         if (disk6.disk[drive].was_gzipped) {
 
             // backup uncompressed data ...
-            char *compressed_data = drive == 0 ? &disk_a_raw[0] : &disk_b_raw[0];
+            uint8_t *compressed_data = drive == 0 ? &disk_a_raw[0] : &disk_b_raw[0];
 
             // re-compress in place ...
             err = zlib_deflate_buffer(/*src:*/disk6.disk[drive].raw_image_data, disk6.disk[drive].whole_len, /*dst:*/compressed_data, &compressed_size);
diff --git a/src/zlib-helpers.c b/src/zlib-helpers.c
index 2bde05be..8bd4b1f6 100644
--- a/src/zlib-helpers.c
+++ b/src/zlib-helpers.c
@@ -31,7 +31,7 @@ static const char* const _gzerr(gzFile gzf) {
     }
 }
 
-static int _gzread_data(gzFile gzsource, char *buf, const int expected_bytescount) {
+static int _gzread_data(gzFile gzsource, uint8_t *buf, const int expected_bytescount) {
     int bytescount = 0;
 
     int maxtries = 10;
@@ -58,7 +58,7 @@ static int _gzread_data(gzFile gzsource, char *buf, const int expected_bytescoun
     return bytescount;
 }
 
-static int _read_data(int fd_own, char *buf, const int expected_bytescount) {
+static int _read_data(int fd_own, uint8_t *buf, const int expected_bytescount) {
     int bytescount = 0;
 
     int maxtries = 10;
@@ -87,7 +87,7 @@ static int _read_data(int fd_own, char *buf, const int expected_bytescount) {
 }
 
 
-static int _write_data(int fd_own, char *buf, const int expected_bytescount) {
+static int _write_data(int fd_own, uint8_t *buf, const int expected_bytescount) {
     int bytescount = 0;
 
     int maxtries = 10;
@@ -121,7 +121,7 @@ static a2gzip_t _check_gzip_magick(int fd_own, const int expected_bytescount) {
     a2gzip_t ret = A2GZT_ERR;
 
     do {
-        char stkbuf[2];
+        uint8_t stkbuf[2];
         int bytescount = _read_data(fd_own, &stkbuf[0], sizeof(stkbuf));
         if (bytescount != sizeof(stkbuf)) {
             ERRLOG("OOPS, could not read file magick for file descriptor");
@@ -158,7 +158,7 @@ static a2gzip_t _check_gzip_magick(int fd_own, const int expected_bytescount) {
  *
  * Return NULL on success, or error string (possibly from zlib) on failure.
  */
-const char *zlib_inflate_to_buffer(int fd, const int expected_bytescount, char *buf) {
+const char *zlib_inflate_to_buffer(int fd, const int expected_bytescount, uint8_t *buf) {
     gzFile gzsource = NULL;
     int fd_own = -1;
 
@@ -254,7 +254,7 @@ const char *zlib_inflate_to_buffer(int fd, const int expected_bytescount, char *
 const char *zlib_inflate_inplace(int fd, const int expected_bytescount, bool *is_gzipped) {
     gzFile gzsource = NULL;
     int fd_own = -1;
-    char *buf = NULL;
+    uint8_t *buf = NULL;
 
     *is_gzipped = false;
 
@@ -374,7 +374,7 @@ const char *zlib_inflate_inplace(int fd, const int expected_bytescount, bool *is
  *
  * Return NULL on success, or error string (possibly from zlib) on failure.
  */
-const char *zlib_deflate_buffer(const char *src, const int src_bytescount, char *dst, OUTPARM off_t *dst_size) {
+const char *zlib_deflate_buffer(const uint8_t *src, const int src_bytescount, uint8_t *dst, OUTPARM off_t *dst_size) {
     char *gzPath = NULL;
     gzFile gzdest = NULL;
     int fd_own = -1;
diff --git a/src/zlib-helpers.h b/src/zlib-helpers.h
index 7ef7df7e..d5932878 100644
--- a/src/zlib-helpers.h
+++ b/src/zlib-helpers.h
@@ -23,13 +23,13 @@
 
 // Inflate/uncompress from file descriptor into previously allocated buffer of expected_bytes length.  Underlying file
 // can either be gzipped or not.  This is meant for readonly disk images.
-const char *zlib_inflate_to_buffer(int fd, const int expected_bytescount, char *buf);
+const char *zlib_inflate_to_buffer(int fd, const int expected_bytescount, uint8_t *buf);
 
 // Inflate/uncompress from file descriptor back into itself.  Underlying file can either be gzipped or not.  This is
 // meant for read/write disk images.
 const char *zlib_inflate_inplace(int fd, const int expected_bytescount, bool *is_gzipped);
 
 // Deflate/compress from buffer to buffer.  This is meant for ejecting read/write disk images.
-const char *zlib_deflate_buffer(const char *src, const int src_bytescount, char *dst, OUTPARM off_t *dst_size);
+const char *zlib_deflate_buffer(const uint8_t *src, const int src_bytescount, uint8_t *dst, OUTPARM off_t *dst_size);
 
 #endif