diff --git a/Modules/_ctypes/callproc.c b/Modules/_ctypes/callproc.c
index 23825a7..cc77e98 100644
--- a/Modules/_ctypes/callproc.c
+++ b/Modules/_ctypes/callproc.c
@@ -25,8 +25,8 @@
 
   2. After several checks, _build_callargs() is called which returns another
   tuple 'callargs'.  This may be the same tuple as 'inargs', a slice of
-  'inargs', or a completely fresh tuple, depending on several things (is is a
-  COM method, are 'paramflags' available).
+  'inargs', or a completely fresh tuple, depending on several things (is it a
+  COM method?, are 'paramflags' available?).
 
   3. _build_callargs also calculates bitarrays containing indexes into
   the callargs tuple, specifying how to build the return value(s) of
diff --git a/Modules/_ctypes/libffi/src/dlmalloc.c b/Modules/_ctypes/libffi/src/dlmalloc.c
index 582ddc3..219f15e 100644
--- a/Modules/_ctypes/libffi/src/dlmalloc.c
+++ b/Modules/_ctypes/libffi/src/dlmalloc.c
@@ -100,7 +100,7 @@
 
        If you don't like either of these options, you can define
        CORRUPTION_ERROR_ACTION and USAGE_ERROR_ACTION to do anything
-       else. And if if you are sure that your program using malloc has
+       else. And if you are sure that your program using malloc has
        no errors or vulnerabilities, you can define INSECURE to 1,
        which might (or might not) provide a small performance improvement.
 
@@ -599,7 +599,7 @@
   declaration needed is the mallinfo struct that is returned (by-copy)
   by mallinfo().  The malloinfo struct contains a bunch of fields that
   are not even meaningful in this version of malloc.  These fields are
-  are instead filled by mallinfo() with other numbers that might be of
+  instead filled by mallinfo() with other numbers that might be of
   interest.
 
   HAVE_USR_INCLUDE_MALLOC_H should be set if you have a
@@ -1564,7 +1564,7 @@
   Each freshly allocated chunk must have both cinuse and pinuse set.
   That is, each allocated chunk borders either a previously allocated
   and still in-use chunk, or the base of its memory arena. This is
-  ensured by making all allocations from the the `lowest' part of any
+  ensured by making all allocations from the `lowest' part of any
   found chunk.  Further, no free chunk physically borders another one,
   so each free chunk is known to be preceded and followed by either
   inuse chunks or the ends of memory.
@@ -1770,12 +1770,12 @@
   of the same size are arranged in a circularly-linked list, with only
   the oldest chunk (the next to be used, in our FIFO ordering)
   actually in the tree.  (Tree members are distinguished by a non-null
-  parent pointer.)  If a chunk with the same size an an existing node
+  parent pointer.)  If a chunk with the same size as an existing node
   is inserted, it is linked off the existing node using pointers that
   work in the same way as fd/bk pointers of small chunks.
 
   Each tree contains a power of 2 sized range of chunk sizes (the
-  smallest is 0x100 <= x < 0x180), which is is divided in half at each
+  smallest is 0x100 <= x < 0x180), which is divided in half at each
   tree level, with the chunks in the smaller half of the range (0x100
   <= x < 0x140 for the top nose) in the left subtree and the larger
   half (0x140 <= x < 0x180) in the right subtree.  This is, of course,
@@ -3380,7 +3380,7 @@
     least-preferred order):
     1. A call to MORECORE that can normally contiguously extend memory.
        (disabled if not MORECORE_CONTIGUOUS or not HAVE_MORECORE or
-       or main space is mmapped or a previous contiguous call failed)
+       main space is mmapped or a previous contiguous call failed)
     2. A call to MMAP new space (disabled if not HAVE_MMAP).
        Note that under the default settings, if MORECORE is unable to
        fulfill a request, and HAVE_MMAP is true, then mmap is
diff --git a/Modules/_ctypes/libffi/src/ia64/ffi.c b/Modules/_ctypes/libffi/src/ia64/ffi.c
index 3f8fcc5..f637834 100644
--- a/Modules/_ctypes/libffi/src/ia64/ffi.c
+++ b/Modules/_ctypes/libffi/src/ia64/ffi.c
@@ -84,7 +84,7 @@
 #define ldf_fill(result, addr)	\
   asm ("ldf.fill %0 = %1%P1" : "=f"(result) : "m"(*addr));
 
-/* Return the size of the C type associated with with TYPE.  Which will
+/* Return the size of the C type associated with TYPE, which will
    be one of the FFI_IA64_TYPE_HFA_* values.  */
 
 static size_t
@@ -184,7 +184,7 @@
       break;
 
     case FFI_TYPE_LONGDOUBLE:
-      /* Similarly, except that that HFA is true for double extended,
+      /* Similarly, except that HFA is true for double extended,
 	 but not quad precision.  Both have sizeof == 16, so tell the
 	 difference based on the precision.  */
       if (LDBL_MANT_DIG == 64 && nested)
diff --git a/Modules/_heapqmodule.c b/Modules/_heapqmodule.c
index 64259de..ec1da05 100644
--- a/Modules/_heapqmodule.c
+++ b/Modules/_heapqmodule.c
@@ -139,7 +139,7 @@
         }
     }
 
-    /* The leaf at pos is empty now.  Put newitem there, and and bubble
+    /* The leaf at pos is empty now.  Put newitem there, and bubble
        it up to its final resting place (by sifting its parents down). */
     Py_DECREF(PyList_GET_ITEM(heap, pos));
     PyList_SET_ITEM(heap, pos, newitem);
@@ -478,7 +478,7 @@
         childpos = 2*pos + 1;
     }
 
-    /* The leaf at pos is empty now.  Put newitem there, and and bubble
+    /* The leaf at pos is empty now.  Put newitem there, and bubble
        it up to its final resting place (by sifting its parents down). */
     Py_DECREF(PyList_GET_ITEM(heap, pos));
     PyList_SET_ITEM(heap, pos, newitem);
diff --git a/Modules/_io/iobase.c b/Modules/_io/iobase.c
index 063ba2e..7505d70 100644
--- a/Modules/_io/iobase.c
+++ b/Modules/_io/iobase.c
@@ -74,7 +74,7 @@
 PyDoc_STRVAR(iobase_seek_doc,
     "Change stream position.\n"
     "\n"
-    "Change the stream position to byte offset offset. offset is\n"
+    "Change the stream position to the given byte offset. The offset is\n"
     "interpreted relative to the position indicated by whence.  Values\n"
     "for whence are:\n"
     "\n"
diff --git a/Modules/expat/xmltok.c b/Modules/expat/xmltok.c
index bf09dfc..b9cd7a4 100644
--- a/Modules/expat/xmltok.c
+++ b/Modules/expat/xmltok.c
@@ -1584,7 +1584,7 @@
       if (ptr[0] == '\0') {
         /* 0 isn't a legal data character. Furthermore a document
            entity can only start with ASCII characters.  So the only
-           way this can fail to be big-endian UTF-16 if it it's an
+           way this can fail to be big-endian UTF-16 is if it is an
            external parsed general entity that's labelled as
            UTF-16LE.
         */
diff --git a/Modules/ossaudiodev.c b/Modules/ossaudiodev.c
index 647a21e..edf1a0e 100644
--- a/Modules/ossaudiodev.c
+++ b/Modules/ossaudiodev.c
@@ -215,7 +215,7 @@
  */
 
 /* _do_ioctl_1() is a private helper function used for the OSS ioctls --
-   SNDCTL_DSP_{SETFMT,CHANNELS,SPEED} -- that that are called from C
+   SNDCTL_DSP_{SETFMT,CHANNELS,SPEED} -- that are called from C
    like this:
      ioctl(fd, SNDCTL_DSP_cmd, &arg)
 
diff --git a/Modules/zlib/deflate.c b/Modules/zlib/deflate.c
index 29ce1f6..4c6df00 100644
--- a/Modules/zlib/deflate.c
+++ b/Modules/zlib/deflate.c
@@ -163,7 +163,7 @@
 
 /* ===========================================================================
  * Update a hash value with the given input byte
- * IN  assertion: all calls to to UPDATE_HASH are made with consecutive
+ * IN  assertion: all calls to UPDATE_HASH are made with consecutive
  *    input characters, so that a running hash key can be computed from the
  *    previous key instead of complete recalculation each time.
  */
@@ -176,7 +176,7 @@
  * the previous length of the hash chain.
  * If this file is compiled with -DFASTEST, the compression level is forced
  * to 1, and no hash chains are maintained.
- * IN  assertion: all calls to to INSERT_STRING are made with consecutive
+ * IN  assertion: all calls to INSERT_STRING are made with consecutive
  *    input characters and the first MIN_MATCH bytes of str are valid
  *    (except for the last MIN_MATCH-1 bytes of the input file).
  */
diff --git a/Modules/zlib/zlib.h b/Modules/zlib/zlib.h
index 0228179..fda7b19 100644
--- a/Modules/zlib/zlib.h
+++ b/Modules/zlib/zlib.h
@@ -764,7 +764,7 @@
     inflateSync returns Z_OK if a 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
+  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.