diff --git a/CMakeLists.txt b/CMakeLists.txt
index 03cb1d64..2f6bbdd0 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -475,7 +475,7 @@ if(UNIX)
     check_c_source_runs("
       #include <stdio.h>
       #include <stdlib.h>
-      int is_shifting_signed (long arg) {
+      static int is_shifting_signed (long arg) {
         long res = arg >> 4;
         if (res == -0x7F7E80CL)
           return 1; /* right shift is signed */
@@ -495,7 +495,7 @@ if(UNIX)
 endif()
 
 if(NOT MSVC OR CMAKE_C_COMPILER_ID STREQUAL "Clang")
-  check_c_source_compiles("const int __attribute__((visibility(\"hidden\"))) table[1] = { 0 }; int main(void) { return table[0]; }"
+  check_c_source_compiles("extern const int table[1]; const int __attribute__((visibility(\"hidden\"))) table[1] = { 0 }; int main(void) { return table[0]; }"
     HIDDEN_WORKS)
   if(HIDDEN_WORKS)
     set(HIDDEN "__attribute__((visibility(\"hidden\")))")
@@ -536,7 +536,7 @@ if(MSVC)
 else()
   set(THREAD_LOCAL "__thread")
 endif()
-check_c_source_compiles("${THREAD_LOCAL} int i;  int main(void) { i = 0;  return i; }"
+check_c_source_compiles("static ${THREAD_LOCAL} int i;  int main(void) { i = 0;  return i; }"
   HAVE_THREAD_LOCAL)
 if(HAVE_THREAD_LOCAL)
   message(STATUS "THREAD_LOCAL = ${THREAD_LOCAL}")
diff --git a/cjpeg.c b/cjpeg.c
index ed649d21..b7385bff 100644
--- a/cjpeg.c
+++ b/cjpeg.c
@@ -7,7 +7,7 @@
  * Lossless JPEG Modifications:
  * Copyright (C) 1999, Ken Murchison.
  * libjpeg-turbo Modifications:
- * Copyright (C) 2010, 2013-2014, 2017, 2019-2022, D. R. Commander.
+ * Copyright (C) 2010, 2013-2014, 2017, 2019-2022, 2024, D. R. Commander.
  * For conditions of distribution and use, see the accompanying README.ijg
  * file.
  *
@@ -156,9 +156,9 @@ select_file_type(j_compress_ptr cinfo, FILE *infile)
 static const char *progname;    /* program name for error messages */
 static char *icc_filename;      /* for -icc switch */
 static char *outfilename;       /* for -outfile switch */
-boolean memdst;                 /* for -memdst switch */
-boolean report;                 /* for -report switch */
-boolean strict;                 /* for -strict switch */
+static boolean memdst;          /* for -memdst switch */
+static boolean report;          /* for -report switch */
+static boolean strict;          /* for -strict switch */
 
 
 #ifdef CJPEG_FUZZER
diff --git a/djpeg.c b/djpeg.c
index 4ea5c4bd..fd30a9ed 100644
--- a/djpeg.c
+++ b/djpeg.c
@@ -5,7 +5,7 @@
  * Copyright (C) 1991-1997, Thomas G. Lane.
  * Modified 2013-2019 by Guido Vollbeding.
  * libjpeg-turbo Modifications:
- * Copyright (C) 2010-2011, 2013-2017, 2019-2020, 2022-2023, D. R. Commander.
+ * Copyright (C) 2010-2011, 2013-2017, 2019-2020, 2022-2024, D. R. Commander.
  * Copyright (C) 2015, Google, Inc.
  * For conditions of distribution and use, see the accompanying README.ijg
  * file.
@@ -84,14 +84,14 @@ static IMAGE_FORMATS requested_fmt;
 
 static const char *progname;    /* program name for error messages */
 static char *icc_filename;      /* for -icc switch */
-JDIMENSION max_scans;           /* for -maxscans switch */
+static JDIMENSION max_scans;    /* for -maxscans switch */
 static char *outfilename;       /* for -outfile switch */
-boolean memsrc;                 /* for -memsrc switch */
-boolean report;                 /* for -report switch */
-boolean skip, crop;
-JDIMENSION skip_start, skip_end;
-JDIMENSION crop_x, crop_y, crop_width, crop_height;
-boolean strict;                 /* for -strict switch */
+static boolean memsrc;          /* for -memsrc switch */
+static boolean report;          /* for -report switch */
+static boolean skip, crop;
+static JDIMENSION skip_start, skip_end;
+static JDIMENSION crop_x, crop_y, crop_width, crop_height;
+static boolean strict;          /* for -strict switch */
 #define INPUT_BUF_SIZE  4096
 
 
diff --git a/jerror.c b/jerror.c
index d0ab5b88..c12c34fc 100644
--- a/jerror.c
+++ b/jerror.c
@@ -4,7 +4,7 @@
  * This file was part of the Independent JPEG Group's software:
  * Copyright (C) 1991-1998, Thomas G. Lane.
  * libjpeg-turbo Modifications:
- * Copyright (C) 2022, D. R. Commander.
+ * Copyright (C) 2022, 2024, D. R. Commander.
  * For conditions of distribution and use, see the accompanying README.ijg
  * file.
  *
@@ -46,7 +46,7 @@
 
 #define JMESSAGE(code, string)  string,
 
-const char * const jpeg_std_message_table[] = {
+static const char * const jpeg_std_message_table[] = {
 #include "jerror.h"
   NULL
 };
diff --git a/jpegtran.c b/jpegtran.c
index d1552ec7..2857a564 100644
--- a/jpegtran.c
+++ b/jpegtran.c
@@ -4,7 +4,7 @@
  * This file was part of the Independent JPEG Group's software:
  * Copyright (C) 1995-2019, Thomas G. Lane, Guido Vollbeding.
  * libjpeg-turbo Modifications:
- * Copyright (C) 2010, 2014, 2017, 2019-2022, D. R. Commander.
+ * Copyright (C) 2010, 2014, 2017, 2019-2022, 2024, D. R. Commander.
  * For conditions of distribution and use, see the accompanying README.ijg
  * file.
  *
@@ -35,11 +35,11 @@
 
 static const char *progname;    /* program name for error messages */
 static char *icc_filename;      /* for -icc switch */
-JDIMENSION max_scans;           /* for -maxscans switch */
+static JDIMENSION max_scans;    /* for -maxscans switch */
 static char *outfilename;       /* for -outfile switch */
 static char *dropfilename;      /* for -drop switch */
-boolean report;                 /* for -report switch */
-boolean strict;                 /* for -strict switch */
+static boolean report;          /* for -report switch */
+static boolean strict;          /* for -strict switch */
 static JCOPY_OPTION copyoption; /* -copy switch */
 static jpeg_transform_info transformoption; /* image transformation options */
 
diff --git a/tjbench.c b/tjbench.c
index bedc94b4..a3592e85 100644
--- a/tjbench.c
+++ b/tjbench.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C)2009-2019, 2021-2023 D. R. Commander.  All Rights Reserved.
+ * Copyright (C)2009-2019, 2021-2024 D. R. Commander.  All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -48,8 +48,8 @@
 }
 #define THROW_UNIX(m)  THROW(m, strerror(errno))
 
-char tjErrorStr[JMSG_LENGTH_MAX] = "\0";
-int tjErrorLine = -1, tjErrorCode = -1;
+static char tjErrorStr[JMSG_LENGTH_MAX] = "\0";
+static int tjErrorLine = -1, tjErrorCode = -1;
 
 #define THROW_TJG() { \
   printf("ERROR in line %d\n%s\n", __LINE__, tj3GetErrorStr(NULL)); \
@@ -88,30 +88,31 @@ int tjErrorLine = -1, tjErrorCode = -1;
   (IS_CROPPED(cr) ? (cr.h != 0 ? cr.h : TJSCALED(height, sf) - cr.y) : \
                     TJSCALED(height, sf))
 
-int stopOnWarning = 0, bottomUp = 0, noRealloc = 1, fastUpsample = 0,
+static int stopOnWarning = 0, bottomUp = 0, noRealloc = 1, fastUpsample = 0,
   fastDCT = 0, optimize = 0, progressive = 0, limitScans = 0, maxMemory = 0,
   maxPixels = 0, arithmetic = 0, lossless = 0, restartIntervalBlocks = 0,
   restartIntervalRows = 0;
-int precision = 8, sampleSize, compOnly = 0, decompOnly = 0, doYUV = 0,
+static int precision = 8, sampleSize, compOnly = 0, decompOnly = 0, doYUV = 0,
   quiet = 0, doTile = 0, pf = TJPF_BGR, yuvAlign = 1, doWrite = 1;
-char *ext = "ppm";
-const char *pixFormatStr[TJ_NUMPF] = {
+static char *ext = "ppm";
+static const char *pixFormatStr[TJ_NUMPF] = {
   "RGB", "BGR", "RGBX", "BGRX", "XBGR", "XRGB", "GRAY", "", "", "", "", "CMYK"
 };
-const char *subNameLong[TJ_NUMSAMP] = {
+static const char *subNameLong[TJ_NUMSAMP] = {
   "4:4:4", "4:2:2", "4:2:0", "GRAY", "4:4:0", "4:1:1", "4:4:1"
 };
-const char *csName[TJ_NUMCS] = {
+static const char *csName[TJ_NUMCS] = {
   "RGB", "YCbCr", "GRAY", "CMYK", "YCCK"
 };
-const char *subName[TJ_NUMSAMP] = {
+static const char *subName[TJ_NUMSAMP] = {
   "444", "422", "420", "GRAY", "440", "411", "441"
 };
-tjscalingfactor *scalingFactors = NULL, sf = { 1, 1 };
-tjregion cr = { 0, 0, 0, 0 };
-int nsf = 0, xformOp = TJXOP_NONE, xformOpt = 0;
-int (*customFilter) (short *, tjregion, tjregion, int, int, tjtransform *);
-double benchTime = 5.0, warmup = 1.0;
+static tjscalingfactor *scalingFactors = NULL, sf = { 1, 1 };
+static tjregion cr = { 0, 0, 0, 0 };
+static int nsf = 0, xformOp = TJXOP_NONE, xformOpt = 0;
+static int (*customFilter) (short *, tjregion, tjregion, int, int,
+                            tjtransform *);
+static double benchTime = 5.0, warmup = 1.0;
 
 
 static char *formatName(int subsamp, int cs, char *buf)
diff --git a/tjexample.c b/tjexample.c
index 1edf30f7..59aa5959 100644
--- a/tjexample.c
+++ b/tjexample.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C)2011-2012, 2014-2015, 2017, 2019, 2021-2023
+ * Copyright (C)2011-2012, 2014-2015, 2017, 2019, 2021-2024
  *           D. R. Commander.  All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -61,16 +61,16 @@
 #define DEFAULT_QUALITY  95
 
 
-const char *subsampName[TJ_NUMSAMP] = {
+static const char *subsampName[TJ_NUMSAMP] = {
   "4:4:4", "4:2:2", "4:2:0", "Grayscale", "4:4:0", "4:1:1", "4:4:1"
 };
 
-const char *colorspaceName[TJ_NUMCS] = {
+static const char *colorspaceName[TJ_NUMCS] = {
   "RGB", "YCbCr", "GRAY", "CMYK", "YCCK"
 };
 
-tjscalingfactor *scalingFactors = NULL;
-int numScalingFactors = 0;
+static tjscalingfactor *scalingFactors = NULL;
+static int numScalingFactors = 0;
 
 
 /* DCT filter example.  This produces a negative of the image. */
diff --git a/tjunittest.c b/tjunittest.c
index dcd5006e..3942833a 100644
--- a/tjunittest.c
+++ b/tjunittest.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C)2009-2014, 2017-2019, 2022-2023 D. R. Commander.
+ * Copyright (C)2009-2014, 2017-2019, 2022-2024 D. R. Commander.
  *                                              All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -83,29 +83,29 @@ static void usage(char *progName)
   BAILOUT() \
 }
 
-const char *subNameLong[TJ_NUMSAMP] = {
+static const char *subNameLong[TJ_NUMSAMP] = {
   "4:4:4", "4:2:2", "4:2:0", "GRAY", "4:4:0", "4:1:1", "4:4:1"
 };
-const char *subName[TJ_NUMSAMP] = {
+static const char *subName[TJ_NUMSAMP] = {
   "444", "422", "420", "GRAY", "440", "411", "441"
 };
 
-const char *pixFormatStr[TJ_NUMPF] = {
+static const char *pixFormatStr[TJ_NUMPF] = {
   "RGB", "BGR", "RGBX", "BGRX", "XBGR", "XRGB", "Grayscale",
   "RGBA", "BGRA", "ABGR", "ARGB", "CMYK"
 };
 
-const int _3sampleFormats[] = { TJPF_RGB, TJPF_BGR };
-const int _4sampleFormats[] = {
+static const int _3sampleFormats[] = { TJPF_RGB, TJPF_BGR };
+static const int _4sampleFormats[] = {
   TJPF_RGBX, TJPF_BGRX, TJPF_XBGR, TJPF_XRGB, TJPF_CMYK
 };
-const int _onlyGray[] = { TJPF_GRAY };
-const int _onlyRGB[] = { TJPF_RGB };
+static const int _onlyGray[] = { TJPF_GRAY };
+static const int _onlyRGB[] = { TJPF_RGB };
 
-int doYUV = 0, lossless = 0, psv = 1, alloc = 0, yuvAlign = 4;
-int precision = 8, sampleSize, maxSample, tolerance, redToY, yellowToY;
+static int doYUV = 0, lossless = 0, psv = 1, alloc = 0, yuvAlign = 4;
+static int precision = 8, sampleSize, maxSample, tolerance, redToY, yellowToY;
 
-int exitStatus = 0;
+static int exitStatus = 0;
 #define BAILOUT() { exitStatus = -1;  goto bailout; }