diff --git a/src/cmake/Config.cmake.in b/src/cmake/Config.cmake.in
index b690864..fb45388 100644
--- a/src/cmake/Config.cmake.in
+++ b/src/cmake/Config.cmake.in
@@ -11,6 +11,9 @@ elseif (@OpenEXR_VERSION@ VERSION_GREATER_EQUAL 2.4 AND @FOUND_OPENEXR_WITH_CONF
                     HINTS @IlmBase_DIR@ @OpenEXR_DIR@)
     find_dependency(OpenEXR @OpenEXR_VERSION@
                     HINTS @OpenEXR_DIR@)
+    find_dependency(libpng CONFIG REQUIRED)
+    find_dependency(libheif CONFIG REQUIRED)
+    find_dependency(unofficial-libsquish CONFIG REQUIRED)
     find_dependency(ZLIB @ZLIB_VERSION@)  # Because OpenEXR doesn't do it
     find_dependency(Threads)  # Because OpenEXR doesn't do it
 endif ()
diff --git a/src/cmake/externalpackages.cmake b/src/cmake/externalpackages.cmake
index 631035a..9f4d096 100644
--- a/src/cmake/externalpackages.cmake
+++ b/src/cmake/externalpackages.cmake
@@ -148,7 +148,7 @@ find_python()
 # Dependencies for optional formats and features. If these are not found,
 # we will continue building, but the related functionality will be disabled.
 
-checked_find_package (PNG)
+checked_find_package (png PREFER_CONFIG)
 
 checked_find_package (BZip2)   # Used by ffmpeg and freetype
 if (NOT BZIP2_FOUND)
@@ -200,7 +200,8 @@ if (ENABLE_FIELD3D)
 endif ()
 
 # For HEIF/HEIC/AVIF formats
-checked_find_package (Libheif VERSION_MIN 1.3
+checked_find_package (libheif VERSION_MIN 1.3
+                      PREFER_CONFIG
                       RECOMMEND_MIN 1.7
                       RECOMMEND_MIN_REASON "for AVIF support")
 if (APPLE AND LIBHEIF_VERSION VERSION_GREATER_EQUAL 1.10 AND LIBHEIF_VERSION VERSION_LESS 1.11)
@@ -307,7 +308,8 @@ endmacro()
 option (USE_EMBEDDED_LIBSQUISH
         "Force use of embedded Libsquish, even if external is found" OFF)
 if (NOT USE_EMBEDDED_LIBSQUISH)
-    checked_find_package (Libsquish)
+    checked_find_package (unofficial-libsquish PREFER_CONFIG)
+    set(libsquish_FOUND 1)
 endif ()
 
 
diff --git a/src/ico.imageio/CMakeLists.txt b/src/ico.imageio/CMakeLists.txt
index d290625..cff954c 100644
--- a/src/ico.imageio/CMakeLists.txt
+++ b/src/ico.imageio/CMakeLists.txt
@@ -2,9 +2,15 @@
 # SPDX-License-Identifier: BSD-3-Clause
 # https://github.com/OpenImageIO/oiio
 
-if (TARGET PNG::PNG)
+if (libpng_FOUND)
+    if (TARGET png_static)
+        set(PNG_TARGET png_static)
+    elseif (TARGET png)
+        set(PNG_TARGET png)
+    endif()
+
     add_oiio_plugin (icoinput.cpp icooutput.cpp
-                     LINK_LIBRARIES PNG::PNG ZLIB::ZLIB)
+                     LINK_LIBRARIES ${PNG_TARGET} ZLIB::ZLIB)
 else ()
     message (WARNING "libpng not found, so ICO support will not work")
     set (format_plugin_definitions ${format_plugin_definitions} DISABLE_ICO=1 PARENT_SCOPE)