diff --git a/CMake/options.cmake b/CMake/options.cmake
index b5150dee2..cc7060bd8 100644
--- a/CMake/options.cmake
+++ b/CMake/options.cmake
@@ -2,7 +2,7 @@
 # Main CMakeLists.txt to build the FLTK project using CMake (www.cmake.org)
 # Originally written by Michael Surette
 #
-# Copyright 1998-2022 by Bill Spitzak and others.
+# Copyright 1998-2023 by Bill Spitzak and others.
 #
 # This library is free software. Distribution and use rights are outlined in
 # the file "COPYING" which should have been included with this file.  If this
@@ -125,12 +125,12 @@ endif ()
 # If either of them is not available, we fall back to using both local libraries
 if (OPTION_USE_SYSTEM_LIBPNG AND NOT (OPTION_USE_SYSTEM_ZLIB AND ZLIB_FOUND))
     set (PNG_FOUND FALSE)
-    set (OPTION_USE_SYSTEM_LIBPNG FALSE)
+    set (OPTION_USE_SYSTEM_LIBPNG OFF)
     message (STATUS "Local z lib selected: overriding png lib to local for compatibility.\n")
 endif ()
 if (OPTION_USE_SYSTEM_ZLIB AND NOT (OPTION_USE_SYSTEM_LIBPNG AND PNG_FOUND))
     set (ZLIB_FOUND FALSE)
-    set (OPTION_USE_SYSTEM_ZLIB FALSE)
+    set (OPTION_USE_SYSTEM_ZLIB OFF)
     message (STATUS "Local png lib selected: overriding z lib to local for compatibility.\n")
 endif ()
 
@@ -951,6 +951,14 @@ if (DEBUG_OPTIONS_CMAKE)
   fl_debug_var (OPENGL_FOUND)
   fl_debug_var (OPENGL_INCLUDE_DIR)
   fl_debug_var (OPENGL_LIBRARIES)
+  fl_debug_var (CMAKE_MSVC_RUNTIME_LIBRARY)
+  message ("--- bundled libraries ---")
+  fl_debug_var (OPTION_USE_SYSTEM_LIBJPEG)
+  fl_debug_var (OPTION_USE_SYSTEM_LIBPNG)
+  fl_debug_var (OPTION_USE_SYSTEM_ZLIB)
+  fl_debug_var (FLTK_USE_BUILTIN_JPEG)
+  fl_debug_var (FLTK_USE_BUILTIN_PNG)
+  fl_debug_var (FLTK_USE_BUILTIN_ZLIB)
   message ("--- X11 ---")
   fl_debug_var (X11_FOUND)
   fl_debug_var (X11_INCLUDE_DIR)
diff --git a/README.CMake.txt b/README.CMake.txt
index c1a40e691..bd03ec4ea 100644
--- a/README.CMake.txt
+++ b/README.CMake.txt
@@ -580,12 +580,12 @@ find_package(FLTK REQUIRED CONFIG)
 
 add_executable(hello WIN32 MACOSX_BUNDLE hello.cxx)
 if (APPLE)
-  target_link_libraries(hello PRIVATE "-framework cocoa")
+  target_link_libraries (hello PRIVATE "-framework cocoa")
 endif (APPLE)
 
-target_include_directories(hello PRIVATE ${FLTK_INCLUDE_DIRS})
+target_include_directories (hello PRIVATE ${FLTK_INCLUDE_DIRS})
 
-target_link_libraries(hello PRIVATE fltk)
+target_link_libraries (hello PRIVATE fltk)
 ---
 
 The set(FLTK_DIR ...) command is a superhint to the find_package command.
@@ -644,12 +644,12 @@ add_custom_command(
 add_executable(CubeView WIN32 MACOSX_BUNDLE
     CubeMain.cxx CubeView.cxx CubeViewUI.cxx)
 
-target_include_directories(CubeView PRIVATE ${FLTK_INCLUDE_DIRS})
+target_include_directories (CubeView PRIVATE ${FLTK_INCLUDE_DIRS})
 
-target_include_directories(CubeView PRIVATE ${CMAKE_CURRENT_BINARY_DIR})
-target_include_directories(CubeView PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
+target_include_directories (CubeView PRIVATE ${CMAKE_CURRENT_BINARY_DIR})
+target_include_directories (CubeView PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
 
-target_link_libraries(CubeView PRIVATE fltk fltk_gl)
+target_link_libraries (CubeView PRIVATE fltk fltk_gl)
 ---
 
 You can repeat the add_custom_command for each fluid file or if you
@@ -658,8 +658,8 @@ FLTK_RUN_FLUID for an example of how to run it in a loop.
 
 The two lines
 
-    target_include_directories(CubeView PRIVATE ${CMAKE_CURRENT_BINARY_DIR})
-    target_include_directories(CubeView PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
+  target_include_directories (CubeView PRIVATE ${CMAKE_CURRENT_BINARY_DIR})
+  target_include_directories (CubeView PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
 
 add the current build ("binary") and source directories as include directories.
 This is necessary for the compiler to find the local header files since the
diff --git a/jpeg/CMakeLists.txt b/jpeg/CMakeLists.txt
index 4b820a02f..f65f71636 100644
--- a/jpeg/CMakeLists.txt
+++ b/jpeg/CMakeLists.txt
@@ -1,7 +1,7 @@
 #
 # JPEG library CMake configuration for the Fast Light Toolkit (FLTK).
 #
-# Copyright 1998-2021 by Bill Spitzak and others.
+# Copyright 1998-2023 by Bill Spitzak and others.
 #
 # This library is free software. Distribution and use rights are outlined in
 # the file "COPYING" which should have been included with this file.  If this
diff --git a/jpeg/Makefile b/jpeg/Makefile
index 6dd48e361..c83b4bb7a 100644
--- a/jpeg/Makefile
+++ b/jpeg/Makefile
@@ -4,7 +4,7 @@
 #
 # JPEG library makefile for the Fast Light Toolkit (FLTK).
 #
-# Copyright 1997-2011 by Bill Spitzak and others.
+# Copyright 1997-2023 by Bill Spitzak and others.
 #
 # This library is free software. Distribution and use rights are outlined in
 # the file "COPYING" which should have been included with this file.  If this
@@ -19,7 +19,6 @@
 
 include ../makeinclude
 
-
 #
 # Object files...
 #
@@ -74,14 +73,12 @@ OBJS	=	\
 
 LIBJPEG	=	../lib/libfltk_jpeg$(LIBEXT)
 
-
 #
 # Make all targets...
 #
 
 all:	$(LIBJPEG)
 
-
 #
 # Clean all targets and object files...
 #
@@ -90,7 +87,6 @@ clean:
 	$(RM) $(OBJS)
 	$(RM) $(LIBJPEG)
 
-
 #
 # Install everything...
 #
@@ -108,7 +104,6 @@ install:	$(LIBJPEG)
 	$(INSTALL_DATA) jpeglib.h $(DESTDIR)$(includedir)/FL/images
 	$(INSTALL_DATA) fltk_jpeg_prefix.h $(DESTDIR)$(includedir)/FL/images
 
-
 #
 # Uninstall everything...
 #
@@ -123,7 +118,6 @@ uninstall:
 	$(RM) $(includedir)/FL/images/jpeglib.h
 	$(RM) $(includedir)/FL/images/fltk_jpeg_prefix.h
 
-
 #
 # libfltk_jpeg.a
 #
@@ -134,7 +128,6 @@ $(LIBJPEG):	$(OBJS)
 	$(LIBCOMMAND) $@ $(OBJS)
 	$(RANLIB) $@
 
-
 #
 # Make dependencies...
 #
diff --git a/png/CMakeLists.txt b/png/CMakeLists.txt
index b47323fe4..c61b1a544 100644
--- a/png/CMakeLists.txt
+++ b/png/CMakeLists.txt
@@ -1,7 +1,7 @@
 #
 # PNG library CMake configuration for the Fast Light Toolkit (FLTK).
 #
-# Copyright 1998-2022 by Bill Spitzak and others.
+# Copyright 1998-2023 by Bill Spitzak and others.
 #
 # This library is free software. Distribution and use rights are outlined in
 # the file "COPYING" which should have been included with this file.  If this
@@ -15,7 +15,7 @@
 #
 
 # source files for png
-set(PNG_SRCS
+set (PNG_SRCS
   png.c
   pngerror.c
   pngget.c
@@ -33,6 +33,13 @@ set(PNG_SRCS
   pngwutil.c
 )
 
+#######################################################################
+# Note: This file is used only if we build the bundled PNG library,
+#  and if we do this we MUST also build and use the *bundled* ZLIB,
+#  hence we MUST also link against the bundled ZLIB (see below).
+#  There's no need to check which ZLIB version to use in this context.
+#######################################################################
+
 #######################################################################
 # Build some files on ARM (e.g. Apple M1 systems)
 #######################################################################
@@ -43,16 +50,16 @@ set(PNG_SRCS
 # This includes all non-macOS platforms.
 
 if (CMAKE_OSX_ARCHITECTURES)
-  string(REGEX MATCH "arm64" is_arm "${CMAKE_OSX_ARCHITECTURES}")
+  string (REGEX MATCH "arm64" is_arm "${CMAKE_OSX_ARCHITECTURES}")
 else ()
   set (is_arm TRUE)
 endif ()
 
 if (is_arm)
   LIST (APPEND PNG_SRCS
-    arm/arm_init.c
-    arm/filter_neon_intrinsics.c
-    arm/palette_neon_intrinsics.c
+        arm/arm_init.c
+        arm/filter_neon_intrinsics.c
+        arm/palette_neon_intrinsics.c
   )
 endif ()
 
@@ -65,8 +72,8 @@ unset (is_arm)
 #######################################################################
 
 LIST (APPEND PNG_SRCS
-  powerpc/powerpc_init.c
-  powerpc/filter_vsx_intrinsics.c
+      powerpc/powerpc_init.c
+      powerpc/filter_vsx_intrinsics.c
 )
 
 #######################################################################
@@ -74,7 +81,7 @@ LIST (APPEND PNG_SRCS
 #######################################################################
 
 FL_ADD_LIBRARY (fltk_png STATIC "${PNG_SRCS}")
-target_link_libraries (fltk_png ${FLTK_ZLIB_LIBRARIES})
+target_link_libraries (fltk_png PUBLIC fltk_z)
 
 #######################################################################
 # Build the shared library (optional)
@@ -83,12 +90,7 @@ target_link_libraries (fltk_png ${FLTK_ZLIB_LIBRARIES})
 if (OPTION_BUILD_SHARED_LIBS)
 
   FL_ADD_LIBRARY (fltk_png SHARED "${PNG_SRCS}")
-
-  if (FLTK_USE_BUILTIN_ZLIB)
-    target_link_libraries (fltk_png_SHARED fltk_z)
-  else()
-    target_link_libraries (fltk_png_SHARED ${FLTK_ZLIB_LIBRARIES})
-  endif ()
+  target_link_libraries (fltk_png_SHARED PUBLIC fltk_z_SHARED)
 
 endif ()
 
diff --git a/png/Makefile b/png/Makefile
index 3326f7a8c..7fd9a8765 100644
--- a/png/Makefile
+++ b/png/Makefile
@@ -2,7 +2,7 @@
 # PNG library Makefile for the Fast Light Toolkit (FLTK).
 #
 # Copyright 1997-2011 by Easy Software Products.
-# Copyright 2012-2020 by Bill Spitzak and others.
+# Copyright 2012-2023 by Bill Spitzak and others.
 #
 # This library is free software. Distribution and use rights are outlined in
 # the file "COPYING" which should have been included with this file.  If this
diff --git a/zlib/CMakeLists.txt b/zlib/CMakeLists.txt
index 1dc30427f..4596a538d 100644
--- a/zlib/CMakeLists.txt
+++ b/zlib/CMakeLists.txt
@@ -1,7 +1,7 @@
 #
 # ZLIB library CMake configuration for the Fast Light Toolkit (FLTK).
 #
-# Copyright 1998-2021 by Bill Spitzak and others.
+# Copyright 1998-2023 by Bill Spitzak and others.
 #
 # This library is free software. Distribution and use rights are outlined in
 # the file "COPYING" which should have been included with this file.  If this
diff --git a/zlib/Makefile b/zlib/Makefile
index c34082679..67fcdd801 100644
--- a/zlib/Makefile
+++ b/zlib/Makefile
@@ -1,7 +1,7 @@
 #
-# GNU ZIP library makefile for the Fast Light Toolkit (FLTK).
+# ZIP library makefile for the Fast Light Toolkit (FLTK).
 #
-# Copyright 1998-2021 by Bill Spitzak and others.
+# Copyright 1998-2023 by Bill Spitzak and others.
 #
 # This library is free software. Distribution and use rights are outlined in
 # the file "COPYING" which should have been included with this file.  If this
@@ -16,7 +16,6 @@
 
 include ../makeinclude
 
-
 #
 # Object files...
 #
@@ -27,14 +26,12 @@ OBJS	=	adler32.o compress.o crc32.o uncompr.o deflate.o \
 
 LIBZ	=	../lib/libfltk_z$(LIBEXT)
 
-
 #
 # Make all targets...
 #
 
 all:	$(LIBZ)
 
-
 #
 # Clean all targets and object files...
 #
@@ -43,7 +40,6 @@ clean:
 	$(RM) $(OBJS)
 	$(RM) $(LIBZ)
 
-
 #
 # Install everything...
 #
@@ -59,7 +55,6 @@ install: $(LIBZ)
 	$(INSTALL_DATA) zlib.h $(DESTDIR)$(includedir)/FL/images
 	$(INSTALL_DATA) zutil.h $(DESTDIR)$(includedir)/FL/images
 
-
 #
 # Uninstall everything...
 #
@@ -72,7 +67,6 @@ uninstall:
 	$(RM) $(includedir)/FL/images/zlib.h
 	$(RM) $(includedir)/FL/images/zutil.h
 
-
 #
 # libfltk_z.a
 #