diff --git a/cmake/InstallAndPackage.cmake b/cmake/InstallAndPackage.cmake
index de01597132..18c10f48c9 100644
--- a/cmake/InstallAndPackage.cmake
+++ b/cmake/InstallAndPackage.cmake
@@ -2,19 +2,19 @@ include(GNUInstallDirs)
 
 # If requested, use FHS layout; otherwise fall back to a flat layout.
 if(OPTION_INSTALL_FHS)
-    set(BINARY_DESTINATION_DIR "${CMAKE_INSTALL_BINDIR}")
-    set(DATA_DESTINATION_DIR "${CMAKE_INSTALL_DATADIR}/${BINARY_NAME}")
-    set(DOCS_DESTINATION_DIR "${CMAKE_INSTALL_DOCDIR}")
-    set(MAN_DESTINATION_DIR "${CMAKE_INSTALL_MANDIR}")
+    cmake_path(SET BINARY_DESTINATION_DIR NORMALIZE "${CMAKE_INSTALL_BINDIR}")
+    cmake_path(SET DATA_DESTINATION_DIR NORMALIZE "${CMAKE_INSTALL_DATADIR}/${BINARY_NAME}")
+    cmake_path(SET DOCS_DESTINATION_DIR NORMALIZE "${CMAKE_INSTALL_DOCDIR}")
+    cmake_path(SET MAN_DESTINATION_DIR NORMALIZE "${CMAKE_INSTALL_MANDIR}")
 else()
     if(APPLE)
-        set(BINARY_DESTINATION_DIR "../MacOS")
+        cmake_path(SET BINARY_DESTINATION_DIR NORMALIZE "../MacOS")
     else()
-        set(BINARY_DESTINATION_DIR ".")
+        cmake_path(SET BINARY_DESTINATION_DIR NORMALIZE ".")
     endif()
-    set(DATA_DESTINATION_DIR ".")
-    set(DOCS_DESTINATION_DIR ".")
-    set(MAN_DESTINATION_DIR ".")
+    cmake_path(SET DATA_DESTINATION_DIR NORMALIZE ".")
+    cmake_path(SET DOCS_DESTINATION_DIR NORMALIZE ".")
+    cmake_path(SET MAN_DESTINATION_DIR NORMALIZE ".")
 endif()
 
 install(TARGETS openttd