diff --git a/contrib/infback9/inftree9.h b/contrib/infback9/inftree9.h
index 2c1252f..ab2ea28 100644
--- a/contrib/infback9/inftree9.h
+++ b/contrib/infback9/inftree9.h
@@ -41,8 +41,8 @@ typedef struct {
    examples/enough.c found in the zlib distribution.  The arguments to that
    program are the number of symbols, the initial root table size, and the
    maximum bit length of a code.  "enough 286 9 15" for literal/length codes
-   returns returns 852, and "enough 32 6 15" for distance codes returns 594.
-   The initial root table size (9 or 6) is found in the fifth argument of the
+   returns 852, and "enough 32 6 15" for distance codes returns 594. The
+   initial root table size (9 or 6) is found in the fifth argument of the
    inflate_table() calls in infback9.c.  If the root table size is changed,
    then these maximum sizes would be need to be recalculated and updated. */
 #define ENOUGH_LENS 852
diff --git a/contrib/minizip/ioapi.h b/contrib/minizip/ioapi.h
index c588a18..a2d2e6e 100644
--- a/contrib/minizip/ioapi.h
+++ b/contrib/minizip/ioapi.h
@@ -144,7 +144,7 @@ typedef long     (ZCALLBACK *tell_file_func)      (voidpf opaque, voidpf stream)
 typedef long     (ZCALLBACK *seek_file_func)      (voidpf opaque, voidpf stream, uLong offset, int origin);
 
 
-/* here is the "old" 32 bits structure structure */
+/* here is the "old" 32 bits structure */
 typedef struct zlib_filefunc_def_s
 {
     open_file_func      zopen_file;
diff --git a/contrib/minizip/zip.c b/contrib/minizip/zip.c
index 86be90b..e2e9da0 100644
--- a/contrib/minizip/zip.c
+++ b/contrib/minizip/zip.c
@@ -614,9 +614,9 @@ local int LoadCentralDirectoryRecord(zip64_internal* pziinit) {
   ZPOS64_T central_pos;
   uLong uL;
 
-  uLong number_disk;          /* number of the current dist, used for
+  uLong number_disk;          /* number of the current disk, used for
                               spanning ZIP, unsupported, always 0*/
-  uLong number_disk_with_CD;  /* number the the disk with central dir, used
+  uLong number_disk_with_CD;  /* number of the disk with central dir, used
                               for spanning ZIP, unsupported, always 0*/
   ZPOS64_T number_entry;
   ZPOS64_T number_entry_CD;      /* total number of entries in
diff --git a/contrib/minizip/zip.h b/contrib/minizip/zip.h
index 5fc0841..3e230d3 100644
--- a/contrib/minizip/zip.h
+++ b/contrib/minizip/zip.h
@@ -177,9 +177,9 @@ extern int ZEXPORT zipOpenNewFileInZip64(zipFile file,
   filename : the filename in zip (if NULL, '-' without quote will be used
   *zipfi contain supplemental information
   if extrafield_local!=NULL and size_extrafield_local>0, extrafield_local
-    contains the extrafield data the the local header
+    contains the extrafield data for the local header
   if extrafield_global!=NULL and size_extrafield_global>0, extrafield_global
-    contains the extrafield data the the local header
+    contains the extrafield data for the global header
   if comment != NULL, comment contain the comment string
   method contain the compression method (0 for store, Z_DEFLATED for deflate)
   level contain the level of compression (can be Z_DEFAULT_COMPRESSION)
diff --git a/inftrees.h b/inftrees.h
index a10712d..396f74b 100644
--- a/inftrees.h
+++ b/inftrees.h
@@ -41,8 +41,8 @@ typedef struct {
    examples/enough.c found in the zlib distribution.  The arguments to that
    program are the number of symbols, the initial root table size, and the
    maximum bit length of a code.  "enough 286 9 15" for literal/length codes
-   returns returns 852, and "enough 30 6 15" for distance codes returns 592.
-   The initial root table size (9 or 6) is found in the fifth argument of the
+   returns 852, and "enough 30 6 15" for distance codes returns 592. The
+   initial root table size (9 or 6) is found in the fifth argument of the
    inflate_table() calls in inflate.c and infback.c.  If the root table size is
    changed, then these maximum sizes would be need to be recalculated and
    updated. */
diff --git a/win32/README-WIN32.txt b/win32/README-WIN32.txt
index 2790e83..600fa3f 100644
--- a/win32/README-WIN32.txt
+++ b/win32/README-WIN32.txt
@@ -16,8 +16,8 @@ is http://zlib.net/ .  Before reporting a problem, please check this site to
 verify that you have the latest version of zlib; otherwise get the latest
 version and check whether the problem still exists or not.
 
-PLEASE read DLL_FAQ.txt, and the the zlib FAQ http://zlib.net/zlib_faq.html
-before asking for help.
+PLEASE read DLL_FAQ.txt, and the zlib FAQ http://zlib.net/zlib_faq.html before
+asking for help.
 
 
 Manifest:
diff --git a/zlib.h b/zlib.h
index ff0fd7e..b3e19fc 100644
--- a/zlib.h
+++ b/zlib.h
@@ -936,10 +936,10 @@ ZEXTERN int ZEXPORT inflateSync(z_streamp strm);
      inflateSync returns Z_OK if a possible full flush point has been found,
    Z_BUF_ERROR if no more input was provided, Z_DATA_ERROR if no flush point
    has been found, or Z_STREAM_ERROR if the stream structure was inconsistent.
-   In the success case, the application may save the current current value of
-   total_in which indicates where valid compressed data was found.  In the
-   error case, the application may repeatedly call inflateSync, providing more
-   input each time, until success or end of the input data.
+   In the success case, the application may save the current value of total_in
+   which indicates where valid compressed data was found.  In the error case,
+   the application may repeatedly call inflateSync, providing more input each
+   time, until success or end of the input data.
 */
 
 ZEXTERN int ZEXPORT inflateCopy(z_streamp dest,