diff --git a/Source/cmMakefile.cxx b/Source/cmMakefile.cxx
index 9b9a3f86d0..b50f0a01f4 100644
--- a/Source/cmMakefile.cxx
+++ b/Source/cmMakefile.cxx
@@ -3511,6 +3511,27 @@ std::string cmMakefile::GetModulesFile(cm::string_view filename, bool& system,
     result = moduleInCMakeRoot;
   }
 
+#if defined(_WIN32) || defined(__APPLE__)
+  if (!result.empty()) {
+    std::string const requestedName =
+      cmSystemTools::GetFilenameName(std::string{ filename });
+    std::string actualName;
+    cmsys::Status const status =
+      cmSystemTools::ReadNameOnDisk(result, actualName);
+    if (status && actualName != requestedName) {
+      this->IssueDiagnostic(
+        cmDiagnostics::CMD_AUTHOR,
+        cmStrCat("The module name\n  ", requestedName, '\n',
+                 "does not match the case of the module file name on disk\n"
+                 "  ",
+                 cmSystemTools::GetFilenamePath(result), '/', actualName, '\n',
+                 "This may fail on case-sensitive file systems.  "
+                 "Use the module name\n  ",
+                 actualName, "\ninstead."));
+    }
+  }
+#endif
+
   return result;
 }
 
diff --git a/Source/cmSystemTools.cxx b/Source/cmSystemTools.cxx
index 485a72eb50..41e6c95557 100644
--- a/Source/cmSystemTools.cxx
+++ b/Source/cmSystemTools.cxx
@@ -367,6 +367,14 @@ RealSystem RealOS;
 
 } // namespace
 
+#if defined(_WIN32) || defined(__APPLE__)
+cmsys::Status cmSystemTools::ReadNameOnDisk(std::string const& path,
+                                            std::string& name)
+{
+  return ::ReadNameOnDisk(path, name);
+}
+#endif
+
 #if !defined(HAVE_ENVIRON_NOT_REQUIRE_PROTOTYPE)
 // For GetEnvironmentVariables
 #  if defined(_WIN32)
diff --git a/Source/cmSystemTools.h b/Source/cmSystemTools.h
index 7eaee0ec5c..31bdf62222 100644
--- a/Source/cmSystemTools.h
+++ b/Source/cmSystemTools.h
@@ -672,6 +672,12 @@ public:
   /** Return subview of the full filename (i.e. file name without path) */
   static cm::string_view GetFilenameNameView(cm::string_view filename);
 
+#if defined(_WIN32) || defined(__APPLE__)
+  /** Read the on-disk spelling of the full filename's last component. */
+  static cmsys::Status ReadNameOnDisk(std::string const& path,
+                                      std::string& name);
+#endif
+
   /**
    * Return subview of file extension of a full filename (dot included).
    * Warning: this is the shortest extension (for example: .gz of .tar.gz)
diff --git a/Tests/CMakeLists.txt b/Tests/CMakeLists.txt
index 441e4de823..8020d96833 100644
--- a/Tests/CMakeLists.txt
+++ b/Tests/CMakeLists.txt
@@ -264,6 +264,22 @@ if(BUILD_TESTING)
     unset(_sysctl_stdout)
   endif()
 
+  if(NOT DEFINED CMake_TEST_FILESYSTEM_CASE)
+    if(CMAKE_HOST_WIN32)
+      set(CMake_TEST_FILESYSTEM_CASE 1)
+    elseif(CMAKE_HOST_APPLE)
+      execute_process(
+        COMMAND sw_vers -productVersion
+        OUTPUT_VARIABLE sw_vers_productVersion
+        OUTPUT_STRIP_TRAILING_WHITESPACE
+        RESULT_VARIABLE _sw_vers_result
+      )
+      if(sw_vers_productVersion VERSION_GREATER_EQUAL 10.11)
+        set(CMake_TEST_FILESYSTEM_CASE 1)
+      endif()
+    endif()
+  endif()
+
   if(CMake_TEST_CUDA AND NOT CMake_TEST_CUDA MATCHES "^(NVIDIA|Clang)$")
     message(FATAL_ERROR "CMake_TEST_CUDA should be \"NVIDIA\" or \"Clang\", got \"${CMake_TEST_CUDA}\"")
   endif()
diff --git a/Tests/RunCMake/CMakeLists.txt b/Tests/RunCMake/CMakeLists.txt
index 1e0fc40652..cdfd0aec16 100644
--- a/Tests/RunCMake/CMakeLists.txt
+++ b/Tests/RunCMake/CMakeLists.txt
@@ -777,7 +777,8 @@ add_RunCMake_test(file-RPATH
 add_RunCMake_test(file-STRINGS)
 add_RunCMake_test(find_file -DMINGW=${MINGW})
 add_RunCMake_test(find_library -DMINGW=${MINGW} -DCYGWIN=${CYGWIN} -DMSYS=${MSYS} -DMSVC=${MSVC})
-add_RunCMake_test(find_package -DMINGW=${MINGW} -DMSYS=${MSYS})
+add_RunCMake_test(find_package -DMINGW=${MINGW} -DMSYS=${MSYS}
+  -DCMake_TEST_FILESYSTEM_CASE=${CMake_TEST_FILESYSTEM_CASE})
 add_RunCMake_test(find_package-CPS)
 add_RunCMake_test(find_path -DMINGW=${MINGW})
 add_RunCMake_test(find_program -DCMAKE_SYSTEM_NAME=${CMAKE_SYSTEM_NAME})
@@ -792,7 +793,7 @@ endif()
 add_RunCMake_test(INSTALL_OBJECT_NAME_STRATEGY)
 add_RunCMake_test(INSTALL_OBJECT_ONLY_USE_DESTINATION)
 add_RunCMake_test(if -DMSYS=${MSYS})
-add_RunCMake_test(include)
+add_RunCMake_test(include -DCMake_TEST_FILESYSTEM_CASE=${CMake_TEST_FILESYSTEM_CASE})
 add_RunCMake_test(include_directories)
 add_RunCMake_test(include_guard)
 add_RunCMake_test(list)
diff --git a/Tests/RunCMake/find_package/ModuleNameCaseMismatch-stderr.txt b/Tests/RunCMake/find_package/ModuleNameCaseMismatch-stderr.txt
new file mode 100644
index 0000000000..c3b26e83bb
--- /dev/null
+++ b/Tests/RunCMake/find_package/ModuleNameCaseMismatch-stderr.txt
@@ -0,0 +1,18 @@
+^CMake Warning \(author\) at ModuleNameCaseMismatch\.cmake:[0-9]+ \(find_package\):
+  The module name
+
+    Findcasemodule\.cmake
+
+  does not match the case of the module file name on disk
+
+    [^
+]*/ModuleNameCaseMismatch/FindCaseModule\.cmake
+
+  This may fail on case-sensitive file systems\.  Use the module name
+
+    FindCaseModule\.cmake
+
+  instead\.
+Call Stack \(most recent call first\):
+  CMakeLists\.txt:[0-9]+ \(include\)
+This warning is for project developers\.  Use -Wno-author to suppress it\.$
diff --git a/Tests/RunCMake/find_package/ModuleNameCaseMismatch.cmake b/Tests/RunCMake/find_package/ModuleNameCaseMismatch.cmake
new file mode 100644
index 0000000000..d3fae60ad1
--- /dev/null
+++ b/Tests/RunCMake/find_package/ModuleNameCaseMismatch.cmake
@@ -0,0 +1,7 @@
+list(PREPEND CMAKE_MODULE_PATH
+  "${CMAKE_CURRENT_LIST_DIR}/ModuleNameCaseMismatch")
+find_package(casemodule MODULE)
+
+if(NOT casemodule_FOUND)
+  message(FATAL_ERROR "FindCaseModule.cmake not included")
+endif()
diff --git a/Tests/RunCMake/find_package/ModuleNameCaseMismatch/FindCaseModule.cmake b/Tests/RunCMake/find_package/ModuleNameCaseMismatch/FindCaseModule.cmake
new file mode 100644
index 0000000000..91a518242f
--- /dev/null
+++ b/Tests/RunCMake/find_package/ModuleNameCaseMismatch/FindCaseModule.cmake
@@ -0,0 +1 @@
+set(casemodule_FOUND TRUE)
diff --git a/Tests/RunCMake/find_package/RunCMakeTest.cmake b/Tests/RunCMake/find_package/RunCMakeTest.cmake
index 1d96eeb745..589eae5ab8 100644
--- a/Tests/RunCMake/find_package/RunCMakeTest.cmake
+++ b/Tests/RunCMake/find_package/RunCMakeTest.cmake
@@ -35,6 +35,9 @@ run_cmake(MissingConfigOneName)
 run_cmake(MissingConfigRequired)
 run_cmake(MissingConfigVersion)
 run_cmake(MixedModeOptions)
+if(CMake_TEST_FILESYSTEM_CASE)
+  run_cmake(ModuleNameCaseMismatch)
+endif()
 run_cmake_with_options(ModuleModeDebugPkg --debug-find-pkg=Foo,Zot)
 run_cmake(NestedConfig)
 run_cmake(PackageRoot)
diff --git a/Tests/RunCMake/include/CaseMismatch-stderr.txt b/Tests/RunCMake/include/CaseMismatch-stderr.txt
new file mode 100644
index 0000000000..1fb4d8a2ee
--- /dev/null
+++ b/Tests/RunCMake/include/CaseMismatch-stderr.txt
@@ -0,0 +1,18 @@
+^CMake Warning \(author\) at CaseMismatch\.cmake:[0-9]+ \(include\):
+  The module name
+
+    casemodule\.cmake
+
+  does not match the case of the module file name on disk
+
+    [^
+]*/CaseMismatch/CaseModule\.cmake
+
+  This may fail on case-sensitive file systems\.  Use the module name
+
+    CaseModule\.cmake
+
+  instead\.
+Call Stack \(most recent call first\):
+  CMakeLists\.txt:[0-9]+ \(include\)
+This warning is for project developers\.  Use -Wno-author to suppress it\.$
diff --git a/Tests/RunCMake/include/CaseMismatch.cmake b/Tests/RunCMake/include/CaseMismatch.cmake
new file mode 100644
index 0000000000..54af68c886
--- /dev/null
+++ b/Tests/RunCMake/include/CaseMismatch.cmake
@@ -0,0 +1,6 @@
+list(PREPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}/CaseMismatch")
+include(casemodule)
+
+if(NOT case_module_included)
+  message(FATAL_ERROR "CaseModule.cmake not included")
+endif()
diff --git a/Tests/RunCMake/include/CaseMismatch/CaseModule.cmake b/Tests/RunCMake/include/CaseMismatch/CaseModule.cmake
new file mode 100644
index 0000000000..cf13bde260
--- /dev/null
+++ b/Tests/RunCMake/include/CaseMismatch/CaseModule.cmake
@@ -0,0 +1 @@
+set(case_module_included TRUE)
diff --git a/Tests/RunCMake/include/RunCMakeTest.cmake b/Tests/RunCMake/include/RunCMakeTest.cmake
index cd5eedbe56..921ebd49a5 100644
--- a/Tests/RunCMake/include/RunCMakeTest.cmake
+++ b/Tests/RunCMake/include/RunCMakeTest.cmake
@@ -6,6 +6,9 @@ run_cmake(CMP0024-NEW)
 run_cmake(ExportExportInclude)
 run_cmake(IncludeIsDirectory)
 run_cmake(IncludeMalformed)
+if(CMake_TEST_FILESYSTEM_CASE)
+  run_cmake(CaseMismatch)
+endif()
 run_cmake(ParentVariableRoot)
 run_cmake(ParentVariableSubDir)
 run_cmake_script(ParentVariableScript)