diff --git a/png.c b/png.c
index 724e6eca2..4cc9d9913 100644
--- a/png.c
+++ b/png.c
@@ -483,7 +483,7 @@ png_get_io_ptr(png_structp png_ptr)
 }
 
 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
-#ifdef PNG_STDIO_SUPPORTED
+#  ifdef PNG_STDIO_SUPPORTED
 /* Initialize the default input/output functions for the PNG file.  If you
  * use your own read or write routines, you can call either png_set_read_fn()
  * or png_set_write_fn() instead of png_init_io().  If you have defined
@@ -500,9 +500,9 @@ png_init_io(png_structp png_ptr, png_FILE_p fp)
 
    png_ptr->io_ptr = (png_voidp)fp;
 }
-#endif
+#  endif
 
-#ifdef PNG_TIME_RFC1123_SUPPORTED
+#  ifdef PNG_TIME_RFC1123_SUPPORTED
 /* Convert the supplied time into an RFC 1123 string suitable for use in
  * a "Creation Time" or other text-based time string.
  */
@@ -521,7 +521,7 @@ png_convert_to_rfc1123(png_structp png_ptr, png_timep ptime)
          png_sizeof(char)));
    }
 
-#ifdef USE_FAR_KEYWORD
+#    ifdef USE_FAR_KEYWORD
    {
       char near_time_buf[29];
       png_snprintf6(near_time_buf, 29, "%d %s %d %02d:%02d:%02d +0000",
@@ -531,15 +531,15 @@ png_convert_to_rfc1123(png_structp png_ptr, png_timep ptime)
       png_memcpy(png_ptr->time_buffer, near_time_buf,
           29*png_sizeof(char));
    }
-#else
+#    else
    png_snprintf6(png_ptr->time_buffer, 29, "%d %s %d %02d:%02d:%02d +0000",
        ptime->day % 32, short_months[(ptime->month - 1) % 12],
        ptime->year, ptime->hour % 24, ptime->minute % 60,
        ptime->second % 61);
-#endif
+#    endif
    return ((png_charp)png_ptr->time_buffer);
 }
-#endif /* PNG_TIME_RFC1123_SUPPORTED */
+#  endif /* PNG_TIME_RFC1123_SUPPORTED */
 
 #endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */
 
@@ -550,19 +550,19 @@ png_get_copyright(png_structp png_ptr)
 #ifdef PNG_STRING_COPYRIGHT
       return PNG_STRING_COPYRIGHT
 #else
-#ifdef __STDC__
+#  ifdef __STDC__
    return ((png_charp) PNG_STRING_NEWLINE \
      "libpng version 1.5.0beta11 - March 3, 2010" PNG_STRING_NEWLINE \
      "Copyright (c) 1998-2010 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \
      "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
      "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
      PNG_STRING_NEWLINE);
-#else
+#  else
       return ((png_charp) "libpng version 1.5.0beta11 - March 3, 2010\
       Copyright (c) 1998-2010 Glenn Randers-Pehrson\
       Copyright (c) 1996-1997 Andreas Dilger\
       Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.");
-#endif
+#  endif
 #endif
 }
 
@@ -597,9 +597,9 @@ png_get_header_version(png_structp png_ptr)
    png_ptr = png_ptr;  /* Silence compiler warning about unused png_ptr */
 #ifdef __STDC__
    return ((png_charp) PNG_HEADER_VERSION_STRING
-#ifndef PNG_READ_SUPPORTED
+#  ifndef PNG_READ_SUPPORTED
    "     (NO READ SUPPORT)"
-#endif
+#  endif
    PNG_STRING_NEWLINE);
 #else
    return ((png_charp) PNG_HEADER_VERSION_STRING);
@@ -607,7 +607,7 @@ png_get_header_version(png_structp png_ptr)
 }
 
 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
-#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
+#  ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
 int PNGAPI
 png_handle_as_unknown(png_structp png_ptr, png_bytep chunk_name)
 {
@@ -622,7 +622,7 @@ png_handle_as_unknown(png_structp png_ptr, png_bytep chunk_name)
         return ((int)*(p + 4));
    return 0;
 }
-#endif
+#  endif
 
 /* This function, added to libpng-1.0.6g, is untested. */
 int PNGAPI
@@ -645,7 +645,7 @@ png_access_version_number(void)
 
 
 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
-#ifdef PNG_SIZE_T
+#  ifdef PNG_SIZE_T
 /* Added at libpng version 1.2.6 */
    PNG_EXTERN png_size_t PNGAPI png_convert_size PNGARG((size_t size));
 png_size_t PNGAPI
@@ -655,11 +655,11 @@ png_convert_size(size_t size)
       PNG_ABORT();  /* We haven't got access to png_ptr, so no png_error() */
    return ((png_size_t)size);
 }
-#endif /* PNG_SIZE_T */
+#  endif /* PNG_SIZE_T */
 
 /* Added at libpng version 1.2.34 and 1.4.0 (moved from pngset.c) */
-#ifdef PNG_cHRM_SUPPORTED
-#ifdef PNG_CHECK_cHRM_SUPPORTED
+#  ifdef PNG_cHRM_SUPPORTED
+#    ifdef PNG_CHECK_cHRM_SUPPORTED
 
 /*
  *    Multiply two 32-bit numbers, V1 and V2, using 32-bit
@@ -770,8 +770,8 @@ png_check_cHRM_fixed(png_structp png_ptr,
 
    return ret;
 }
-#endif /* PNG_CHECK_cHRM_SUPPORTED */
-#endif /* PNG_cHRM_SUPPORTED */
+#    endif /* PNG_CHECK_cHRM_SUPPORTED */
+#  endif /* PNG_cHRM_SUPPORTED */
 
 void /* PRIVATE */
 png_check_IHDR(png_structp png_ptr,
@@ -794,21 +794,21 @@ png_check_IHDR(png_structp png_ptr,
       error = 1;
    }
 
-#ifdef PNG_SET_USER_LIMITS_SUPPORTED
+#  ifdef PNG_SET_USER_LIMITS_SUPPORTED
    if (width > png_ptr->user_width_max || width > PNG_USER_WIDTH_MAX)
-#else
+#  else
    if (width > PNG_USER_WIDTH_MAX)
-#endif
+#  endif
    {
       png_warning(png_ptr, "Image width exceeds user limit in IHDR");
       error = 1;
    }
 
-#ifdef PNG_SET_USER_LIMITS_SUPPORTED
+#  ifdef PNG_SET_USER_LIMITS_SUPPORTED
    if (height > png_ptr->user_height_max || height > PNG_USER_HEIGHT_MAX)
-#else
+#  else
    if (height > PNG_USER_HEIGHT_MAX)
-#endif
+#  endif
    {
       png_warning(png_ptr, "Image height exceeds user limit in IHDR");
       error = 1;
@@ -870,7 +870,7 @@ png_check_IHDR(png_structp png_ptr,
       error = 1;
    }
 
-#ifdef PNG_MNG_FEATURES_SUPPORTED
+#  ifdef PNG_MNG_FEATURES_SUPPORTED
    /* Accept filter_method 64 (intrapixel differencing) only if
     * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
     * 2. Libpng did not read a PNG signature (this filter_method is only
@@ -903,13 +903,13 @@ png_check_IHDR(png_structp png_ptr,
       }
    }
 
-#else
+#  else
    if (filter_type != PNG_FILTER_TYPE_BASE)
    {
       png_warning(png_ptr, "Unknown filter method in IHDR");
       error = 1;
    }
-#endif
+#  endif
 
    if (error == 1)
       png_error(png_ptr, "Invalid IHDR data");
diff --git a/pngmem.c b/pngmem.c
index c9177f739..3ea55ac71 100644
--- a/pngmem.c
+++ b/pngmem.c
@@ -32,7 +32,7 @@
 png_voidp /* PRIVATE */
 png_create_struct(int type)
 {
-#ifdef PNG_USER_MEM_SUPPORTED
+#  ifdef PNG_USER_MEM_SUPPORTED
    return (png_create_struct_2(type, NULL, NULL));
 }
 
@@ -40,7 +40,7 @@ png_create_struct(int type)
 png_voidp /* PRIVATE */
 png_create_struct_2(int type, png_malloc_ptr malloc_fn, png_voidp mem_ptr)
 {
-#endif /* PNG_USER_MEM_SUPPORTED */
+#  endif /* PNG_USER_MEM_SUPPORTED */
    png_size_t size;
    png_voidp struct_ptr;
 
@@ -51,7 +51,7 @@ png_create_struct_2(int type, png_malloc_ptr malloc_fn, png_voidp mem_ptr)
    else
       return (png_get_copyright(NULL));
 
-#ifdef PNG_USER_MEM_SUPPORTED
+#  ifdef PNG_USER_MEM_SUPPORTED
    if (malloc_fn != NULL)
    {
       png_struct dummy_struct;
@@ -60,7 +60,7 @@ png_create_struct_2(int type, png_malloc_ptr malloc_fn, png_voidp mem_ptr)
       struct_ptr = (*(malloc_fn))(png_ptr, (png_uint_32)size);
    }
    else
-#endif /* PNG_USER_MEM_SUPPORTED */
+#  endif /* PNG_USER_MEM_SUPPORTED */
    struct_ptr = (png_voidp)farmalloc(size);
    if (struct_ptr != NULL)
       png_memset(struct_ptr, 0, size);
@@ -71,7 +71,7 @@ png_create_struct_2(int type, png_malloc_ptr malloc_fn, png_voidp mem_ptr)
 void /* PRIVATE */
 png_destroy_struct(png_voidp struct_ptr)
 {
-#ifdef PNG_USER_MEM_SUPPORTED
+#  ifdef PNG_USER_MEM_SUPPORTED
    png_destroy_struct_2(struct_ptr, NULL, NULL);
 }
 
@@ -80,10 +80,10 @@ void /* PRIVATE */
 png_destroy_struct_2(png_voidp struct_ptr, png_free_ptr free_fn,
     png_voidp mem_ptr)
 {
-#endif
+#  endif
    if (struct_ptr != NULL)
    {
-#ifdef PNG_USER_MEM_SUPPORTED
+#  ifdef PNG_USER_MEM_SUPPORTED
       if (free_fn != NULL)
       {
          png_struct dummy_struct;
@@ -92,7 +92,7 @@ png_destroy_struct_2(png_voidp struct_ptr, png_free_ptr free_fn,
          (*(free_fn))(png_ptr, struct_ptr);
          return;
       }
-#endif /* PNG_USER_MEM_SUPPORTED */
+#  endif /* PNG_USER_MEM_SUPPORTED */
       farfree (struct_ptr);
    }
 }
@@ -135,7 +135,7 @@ png_malloc(png_structp png_ptr, png_alloc_size_t size)
    if (png_ptr == NULL || size == 0)
       return (NULL);
 
-#ifdef PNG_USER_MEM_SUPPORTED
+#  ifdef PNG_USER_MEM_SUPPORTED
    if (png_ptr->malloc_fn != NULL)
       ret = ((png_voidp)(*(png_ptr->malloc_fn))(png_ptr, (png_size_t)size));
    else
@@ -149,19 +149,19 @@ png_voidp PNGAPI
 png_malloc_default(png_structp png_ptr, png_alloc_size_t size)
 {
    png_voidp ret;
-#endif /* PNG_USER_MEM_SUPPORTED */
+#  endif /* PNG_USER_MEM_SUPPORTED */
 
    if (png_ptr == NULL || size == 0)
       return (NULL);
 
-#ifdef PNG_MAX_MALLOC_64K
+#  ifdef PNG_MAX_MALLOC_64K
    if (size > (png_uint_32)65536L)
    {
       png_warning(png_ptr, "Cannot Allocate > 64K");
       ret = NULL;
    }
    else
-#endif
+#  endif
 
    if (size != (size_t)size)
       ret = NULL;
@@ -200,25 +200,25 @@ png_malloc_default(png_structp png_ptr, png_alloc_size_t size)
 
             if (table == NULL)
             {
-#ifndef PNG_USER_MEM_SUPPORTED
+#  ifndef PNG_USER_MEM_SUPPORTED
                if ((png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
                   png_error(png_ptr, "Out Of Memory"); /* Note "O", "M" */
                else
                   png_warning(png_ptr, "Out Of Memory");
-#endif
+#  endif
                return (NULL);
             }
 
             if ((png_size_t)table & 0xfff0)
             {
-#ifndef PNG_USER_MEM_SUPPORTED
+#  ifndef PNG_USER_MEM_SUPPORTED
                if ((png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
                   png_error(png_ptr,
                     "Farmalloc didn't return normalized pointer");
                else
                   png_warning(png_ptr,
                     "Farmalloc didn't return normalized pointer");
-#endif
+#  endif
                return (NULL);
             }
 
@@ -228,12 +228,12 @@ png_malloc_default(png_structp png_ptr, png_alloc_size_t size)
 
             if (png_ptr->offset_table_ptr == NULL)
             {
-#ifndef PNG_USER_MEM_SUPPORTED
+#  ifndef PNG_USER_MEM_SUPPORTED
                if ((png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
                   png_error(png_ptr, "Out Of memory"); /* Note "O", "m" */
                else
                   png_warning(png_ptr, "Out Of memory");
-#endif
+#  endif
                return (NULL);
             }
 
@@ -257,12 +257,12 @@ png_malloc_default(png_structp png_ptr, png_alloc_size_t size)
 
       if (png_ptr->offset_table_count >= png_ptr->offset_table_number)
       {
-#ifndef PNG_USER_MEM_SUPPORTED
+#  ifndef PNG_USER_MEM_SUPPORTED
          if ((png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
             png_error(png_ptr, "Out of Memory"); /* Note "o" and "M" */
          else
             png_warning(png_ptr, "Out of Memory");
-#endif
+#  endif
          return (NULL);
       }
 
@@ -271,7 +271,7 @@ png_malloc_default(png_structp png_ptr, png_alloc_size_t size)
    else
       ret = farmalloc(size);
 
-#ifndef PNG_USER_MEM_SUPPORTED
+#  ifndef PNG_USER_MEM_SUPPORTED
    if (ret == NULL)
    {
       if ((png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
@@ -279,7 +279,7 @@ png_malloc_default(png_structp png_ptr, png_alloc_size_t size)
       else
          png_warning(png_ptr, "Out of memory"); /* Note "o" and "m" */
    }
-#endif
+#  endif
 
    return (ret);
 }
@@ -294,7 +294,7 @@ png_free(png_structp png_ptr, png_voidp ptr)
    if (png_ptr == NULL || ptr == NULL)
       return;
 
-#ifdef PNG_USER_MEM_SUPPORTED
+#  ifdef PNG_USER_MEM_SUPPORTED
    if (png_ptr->free_fn != NULL)
    {
       (*(png_ptr->free_fn))(png_ptr, ptr);
@@ -307,7 +307,7 @@ png_free(png_structp png_ptr, png_voidp ptr)
 void PNGAPI
 png_free_default(png_structp png_ptr, png_voidp ptr)
 {
-#endif /* PNG_USER_MEM_SUPPORTED */
+#  endif /* PNG_USER_MEM_SUPPORTED */
 
    if (png_ptr == NULL || ptr == NULL)
       return;
@@ -348,7 +348,7 @@ png_free_default(png_structp png_ptr, png_voidp ptr)
 png_voidp /* PRIVATE */
 png_create_struct(int type)
 {
-#ifdef PNG_USER_MEM_SUPPORTED
+#  ifdef PNG_USER_MEM_SUPPORTED
    return (png_create_struct_2(type, NULL, NULL));
 }
 
@@ -358,7 +358,7 @@ png_create_struct(int type)
 png_voidp /* PRIVATE */
 png_create_struct_2(int type, png_malloc_ptr malloc_fn, png_voidp mem_ptr)
 {
-#endif /* PNG_USER_MEM_SUPPORTED */
+#  endif /* PNG_USER_MEM_SUPPORTED */
    png_size_t size;
    png_voidp struct_ptr;
 
@@ -369,7 +369,7 @@ png_create_struct_2(int type, png_malloc_ptr malloc_fn, png_voidp mem_ptr)
    else
       return (NULL);
 
-#ifdef PNG_USER_MEM_SUPPORTED
+#  ifdef PNG_USER_MEM_SUPPORTED
    if (malloc_fn != NULL)
    {
       png_struct dummy_struct;
@@ -380,17 +380,17 @@ png_create_struct_2(int type, png_malloc_ptr malloc_fn, png_voidp mem_ptr)
          png_memset(struct_ptr, 0, size);
       return (struct_ptr);
    }
-#endif /* PNG_USER_MEM_SUPPORTED */
+#  endif /* PNG_USER_MEM_SUPPORTED */
 
-#if defined(__TURBOC__) && !defined(__FLAT__)
+#  if defined(__TURBOC__) && !defined(__FLAT__)
    struct_ptr = (png_voidp)farmalloc(size);
-#else
-# if defined(_MSC_VER) && defined(MAXSEG_64K)
+#  else
+#    if defined(_MSC_VER) && defined(MAXSEG_64K)
    struct_ptr = (png_voidp)halloc(size, 1);
-# else
+#    else
    struct_ptr = (png_voidp)malloc(size);
-# endif
-#endif
+#    endif
+#  endif
    if (struct_ptr != NULL)
       png_memset(struct_ptr, 0, size);
 
@@ -402,7 +402,7 @@ png_create_struct_2(int type, png_malloc_ptr malloc_fn, png_voidp mem_ptr)
 void /* PRIVATE */
 png_destroy_struct(png_voidp struct_ptr)
 {
-#ifdef PNG_USER_MEM_SUPPORTED
+#  ifdef PNG_USER_MEM_SUPPORTED
    png_destroy_struct_2(struct_ptr, NULL, NULL);
 }
 
@@ -411,10 +411,10 @@ void /* PRIVATE */
 png_destroy_struct_2(png_voidp struct_ptr, png_free_ptr free_fn,
     png_voidp mem_ptr)
 {
-#endif /* PNG_USER_MEM_SUPPORTED */
+#  endif /* PNG_USER_MEM_SUPPORTED */
    if (struct_ptr != NULL)
    {
-#ifdef PNG_USER_MEM_SUPPORTED
+#  ifdef PNG_USER_MEM_SUPPORTED
       if (free_fn != NULL)
       {
          png_struct dummy_struct;
@@ -423,16 +423,16 @@ png_destroy_struct_2(png_voidp struct_ptr, png_free_ptr free_fn,
          (*(free_fn))(png_ptr, struct_ptr);
          return;
       }
-#endif /* PNG_USER_MEM_SUPPORTED */
-#if defined(__TURBOC__) && !defined(__FLAT__)
+#  endif /* PNG_USER_MEM_SUPPORTED */
+#  if defined(__TURBOC__) && !defined(__FLAT__)
       farfree(struct_ptr);
-#else
-# if defined(_MSC_VER) && defined(MAXSEG_64K)
+#  else
+#    if defined(_MSC_VER) && defined(MAXSEG_64K)
       hfree(struct_ptr);
-# else
+#    else
       free(struct_ptr);
-# endif
-#endif
+#    endif
+#  endif
    }
 }
 
@@ -459,7 +459,7 @@ png_malloc(png_structp png_ptr, png_alloc_size_t size)
 {
    png_voidp ret;
 
-#ifdef PNG_USER_MEM_SUPPORTED
+#  ifdef PNG_USER_MEM_SUPPORTED
    if (png_ptr == NULL || size == 0)
       return (NULL);
 
@@ -476,47 +476,47 @@ png_voidp PNGAPI
 png_malloc_default(png_structp png_ptr, png_alloc_size_t size)
 {
    png_voidp ret;
-#endif /* PNG_USER_MEM_SUPPORTED */
+#  endif /* PNG_USER_MEM_SUPPORTED */
 
    if (png_ptr == NULL || size == 0)
       return (NULL);
 
-#ifdef PNG_MAX_MALLOC_64K
+#  ifdef PNG_MAX_MALLOC_64K
    if (size > (png_uint_32)65536L)
    {
-#ifndef PNG_USER_MEM_SUPPORTED
+#    ifndef PNG_USER_MEM_SUPPORTED
       if ((png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
          png_error(png_ptr, "Cannot Allocate > 64K");
       else
-#endif
+#    endif
          return NULL;
    }
-#endif
+#  endif
 
    /* Check for overflow */
-#if defined(__TURBOC__) && !defined(__FLAT__)
+#  if defined(__TURBOC__) && !defined(__FLAT__)
    if (size != (unsigned long)size)
       ret = NULL;
    else
       ret = farmalloc(size);
-#else
-# if defined(_MSC_VER) && defined(MAXSEG_64K)
+#  else
+#    if defined(_MSC_VER) && defined(MAXSEG_64K)
    if (size != (unsigned long)size)
       ret = NULL;
    else
       ret = halloc(size, 1);
-# else
+#    else
    if (size != (size_t)size)
       ret = NULL;
    else
       ret = malloc((size_t)size);
-# endif
-#endif
+#    endif
+#  endif
 
-#ifndef PNG_USER_MEM_SUPPORTED
+#  ifndef PNG_USER_MEM_SUPPORTED
    if (ret == NULL && (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
       png_error(png_ptr, "Out of Memory");
-#endif
+#  endif
 
    return (ret);
 }
@@ -530,7 +530,7 @@ png_free(png_structp png_ptr, png_voidp ptr)
    if (png_ptr == NULL || ptr == NULL)
       return;
 
-#ifdef PNG_USER_MEM_SUPPORTED
+#  ifdef PNG_USER_MEM_SUPPORTED
    if (png_ptr->free_fn != NULL)
    {
       (*(png_ptr->free_fn))(png_ptr, ptr);
@@ -545,17 +545,17 @@ png_free_default(png_structp png_ptr, png_voidp ptr)
    if (png_ptr == NULL || ptr == NULL)
       return;
 
-#endif /* PNG_USER_MEM_SUPPORTED */
+#  endif /* PNG_USER_MEM_SUPPORTED */
 
-#if defined(__TURBOC__) && !defined(__FLAT__)
+#  if defined(__TURBOC__) && !defined(__FLAT__)
    farfree(ptr);
-#else
-# if defined(_MSC_VER) && defined(MAXSEG_64K)
+#  else
+#    if defined(_MSC_VER) && defined(MAXSEG_64K)
    hfree(ptr);
-# else
+#    else
    free(ptr);
-# endif
-#endif
+#    endif
+#  endif
 }
 
 #endif /* Not Borland DOS special memory handler */
diff --git a/pngrio.c b/pngrio.c
index 8d77ab347..91d1e2d7a 100644
--- a/pngrio.c
+++ b/pngrio.c
@@ -47,7 +47,7 @@ png_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
  * read_data function and use it at run time with png_set_read_fn(), rather
  * than changing the library.
  */
-#ifndef USE_FAR_KEYWORD
+#  ifndef USE_FAR_KEYWORD
 void PNGAPI
 png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
 {
@@ -63,7 +63,7 @@ png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
    if (check != length)
       png_error(png_ptr, "Read Error");
 }
-#else
+#  else
 /* This is the model-independent version. Since the standard I/O library
    can't handle far buffers in the medium and small models, we have to copy
    the data.
@@ -111,7 +111,7 @@ png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
    if ((png_uint_32)check != (png_uint_32)length)
       png_error(png_ptr, "read Error");
 }
-#endif
+#  endif
 #endif
 
 /* This function allows the application to supply a new input function
diff --git a/pngwio.c b/pngwio.c
index 643b66542..f8dda215a 100644
--- a/pngwio.c
+++ b/pngwio.c
@@ -124,7 +124,7 @@ png_flush(png_structp png_ptr)
       (*(png_ptr->output_flush_fn))(png_ptr);
 }
 
-#ifdef PNG_STDIO_SUPPORTED
+#  ifdef PNG_STDIO_SUPPORTED
 void PNGAPI
 png_default_flush(png_structp png_ptr)
 {
@@ -134,7 +134,7 @@ png_default_flush(png_structp png_ptr)
    io_ptr = (png_FILE_p)CVT_PTR((png_ptr->io_ptr));
    fflush(io_ptr);
 }
-#endif
+#  endif
 #endif
 
 /* This function allows the application to supply new output functions for
@@ -168,7 +168,7 @@ png_default_flush(png_structp png_ptr)
  */
 void PNGAPI
 png_set_write_fn(png_structp png_ptr, png_voidp io_ptr,
-   png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn)
+    png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn)
 {
    if (png_ptr == NULL)
       return;
@@ -186,15 +186,15 @@ png_set_write_fn(png_structp png_ptr, png_voidp io_ptr,
 #endif
 
 #ifdef PNG_WRITE_FLUSH_SUPPORTED
-#ifdef PNG_STDIO_SUPPORTED
+#  ifdef PNG_STDIO_SUPPORTED
    if (output_flush_fn != NULL)
       png_ptr->output_flush_fn = output_flush_fn;
 
    else
       png_ptr->output_flush_fn = png_default_flush;
-#else
+#  else
    png_ptr->output_flush_fn = output_flush_fn;
-#endif
+#  endif
 #endif /* PNG_WRITE_FLUSH_SUPPORTED */
 
    /* It is an error to read while writing a png file */
@@ -209,7 +209,7 @@ png_set_write_fn(png_structp png_ptr, png_voidp io_ptr,
 }
 
 #ifdef USE_FAR_KEYWORD
-#ifdef _MSC_VER
+#  ifdef _MSC_VER
 void *png_far_to_near(png_structp png_ptr, png_voidp ptr, int check)
 {
    void *near_ptr;
@@ -237,6 +237,6 @@ void *png_far_to_near(png_structp png_ptr, png_voidp ptr, int check)
 
    return(near_ptr);
 }
-#   endif
-#   endif
+#  endif
+#endif
 #endif /* PNG_WRITE_SUPPORTED */