diff --git a/src/calibre/utils/lzx/compressor.c b/src/calibre/utils/lzx/compressor.c
index cf3c3f6e92..1c496a5c27 100644
--- a/src/calibre/utils/lzx/compressor.c
+++ b/src/calibre/utils/lzx/compressor.c
@@ -21,7 +21,7 @@
      + ((compressor)->input.size - (compressor)->input.offset))
 
 typedef struct buffer_t {
-    void *data;
+    char *data;
     unsigned int size;
     unsigned int offset;
 } buffer_t;
@@ -222,7 +222,7 @@ Compressor_init(Compressor *self, PyObject *args, PyObject *kwds)
 
 static PyObject *
 Compressor_compress__(
-    Compressor *self, unsigned char *data, unsigned int inlen, int flush)
+    Compressor *self, char *data, unsigned int inlen, int flush)
 {
     buffer_t *residue = &self->residue;
     buffer_t *input = &self->input;
@@ -305,7 +305,7 @@ static PyObject *
 Compressor_compress(Compressor *self, PyObject *args, PyObject *kwds)
 {
     static char *kwlist[] = {"data", "flush", NULL};
-    unsigned char *data = NULL;
+    char *data = NULL;
     unsigned int inlen = 0;
     int flush = 0;
 
diff --git a/src/calibre/utils/lzx/lzxc.c b/src/calibre/utils/lzx/lzxc.c
index c5ad518bc2..ac1a5ed2a1 100644
--- a/src/calibre/utils/lzx/lzxc.c
+++ b/src/calibre/utils/lzx/lzxc.c
@@ -23,7 +23,11 @@
 
 #include <stdio.h>
 #include <stdlib.h>
-#include <stdint.h>
+#ifdef _MSC_VER
+# include "msstdint.h"
+#else /* _MSC_VER */
+# include <stdint.h>
+#endif /* _MSC_VER */
 #include <string.h> /* for memset on Linux */
 #include <assert.h>
 #include <math.h>
diff --git a/src/calibre/utils/lzx/stdint.h b/src/calibre/utils/lzx/msstdint.h
similarity index 100%
rename from src/calibre/utils/lzx/stdint.h
rename to src/calibre/utils/lzx/msstdint.h