diff --git a/IlmBase/config/CMakeLists.txt b/IlmBase/config/CMakeLists.txt
index dfebb43bd0..8b0eae7fcb 100644
--- a/IlmBase/config/CMakeLists.txt
+++ b/IlmBase/config/CMakeLists.txt
@@ -5,6 +5,7 @@ include(CheckIncludeFiles)
 include(CheckSymbolExists)
 include(CheckLibraryExists)
 include(CheckStructHasMember)
+include(../../cmake/JoinPaths.cmake)
 
 check_include_files(ucontext.h ILMBASE_HAVE_UCONTEXT_H)
 if(ILMBASE_HAVE_UCONTEXT_H)
@@ -76,8 +77,8 @@ if(ILMBASE_INSTALL_PKG_CONFIG)
   function(ilmbase_pkg_config_help pcinfile)
     set(prefix ${CMAKE_INSTALL_PREFIX})
     set(exec_prefix "\${prefix}")
-    set(libdir "\${exec_prefix}/${CMAKE_INSTALL_LIBDIR}")
-    set(includedir "\${prefix}/${CMAKE_INSTALL_INCLUDEDIR}")
+    join_paths(libdir "\${exec_prefix}" "${CMAKE_INSTALL_LIBDIR}")
+    join_paths(includedir "\${prefix}" "${CMAKE_INSTALL_INCLUDEDIR}")
     string(TOUPPER "${CMAKE_BUILD_TYPE}" uppercase_CMAKE_BUILD_TYPE)
     set(LIB_SUFFIX_DASH ${ILMBASE_LIB_SUFFIX}${CMAKE_${uppercase_CMAKE_BUILD_TYPE}_POSTFIX})
     if(TARGET Threads::Threads)
diff --git a/OpenEXR/config/CMakeLists.txt b/OpenEXR/config/CMakeLists.txt
index 039190cd90..d13ee16ee9 100644
--- a/OpenEXR/config/CMakeLists.txt
+++ b/OpenEXR/config/CMakeLists.txt
@@ -6,6 +6,7 @@ include(CheckSymbolExists)
 include(CheckLibraryExists)
 include(CheckStructHasMember)
 include(CheckCXXSourceCompiles)
+include(../../cmake/JoinPaths.cmake)
 
 if (NOT CMAKE_CROSSCOMPILING AND EXISTS "/proc/self/exe")
   set(OPENEXR_IMF_HAVE_LINUX_PROCFS TRUE)
@@ -75,8 +76,8 @@ if(OPENEXR_INSTALL_PKG_CONFIG)
   function(openexr_pkg_config_help pcinfile)
     set(prefix ${CMAKE_INSTALL_PREFIX})
     set(exec_prefix "\${prefix}")
-    set(libdir "\${exec_prefix}/${CMAKE_INSTALL_LIBDIR}")
-    set(includedir "\${prefix}/${CMAKE_INSTALL_INCLUDEDIR}")
+    join_paths(libdir "\${exec_prefix}" "${CMAKE_INSTALL_LIBDIR}")
+    join_paths(includedir "\${prefix}" "${CMAKE_INSTALL_INCLUDEDIR}")
     string(TOUPPER "${CMAKE_BUILD_TYPE}" uppercase_CMAKE_BUILD_TYPE)
     set(LIB_SUFFIX_DASH ${OPENEXR_LIB_SUFFIX}${CMAKE_${uppercase_CMAKE_BUILD_TYPE}_POSTFIX})
     if(TARGET Threads::Threads)
diff --git a/cmake/JoinPaths.cmake b/cmake/JoinPaths.cmake
new file mode 100644
index 0000000000..b5bc2e57f8
--- /dev/null
+++ b/cmake/JoinPaths.cmake
@@ -0,0 +1,23 @@
+# This module provides function for joining paths
+# known from from most languages
+#
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright Contributors to the OpenEXR Project.
+# https://github.com/jtojnar/cmake-snips
+#
+# Modelled after Python’s os.path.join
+# https://docs.python.org/3.7/library/os.path.html#os.path.join
+# Windows not supported
+function(join_paths joined_path first_path_segment)
+    set(temp_path "${first_path_segment}")
+    foreach(current_segment IN LISTS ARGN)
+        if(NOT ("${current_segment}" STREQUAL ""))
+            if(IS_ABSOLUTE "${current_segment}")
+                set(temp_path "${current_segment}")
+            else()
+                set(temp_path "${temp_path}/${current_segment}")
+            endif()
+        endif()
+    endforeach()
+    set(${joined_path} "${temp_path}" PARENT_SCOPE)
+endfunction()