diff --git a/avogadro/lastinstall/CMakeLists.txt b/avogadro/lastinstall/CMakeLists.txt
index 6bc695a9..0a9a2097 100644
--- a/avogadro/lastinstall/CMakeLists.txt
+++ b/avogadro/lastinstall/CMakeLists.txt
@@ -38,10 +38,15 @@ if((APPLE OR WIN32) AND NOT ${CMAKE_VERSION} VERSION_LESS 2.8.8)
     if(EXISTS "${Qt5_Dir}/../../Tools/OpenSSLv3/Win_x64/")
       set(OPENSSL_ROOT_DIR "${Qt5_Dir}/../../Tools/OpenSSLv3/Win_x64/")
       message(STATUS "Using OpenSSL from ${OPENSSL_ROOT_DIR}")
+    elseif(DEFINED $ENV{OPENSSL_ROOT_DIR})
+      set(OPENSSL_ROOT_DIR $ENV{OPENSSL_ROOT_DIR})
+      message(STATUS "Using OpenSSL from ${OPENSSL_ROOT_DIR}")
+    endif()
+    if (DEFINED OPENSSL_ROOT_DIR)
       file(GLOB OPENSSL_DLL ${OPENSSL_ROOT_DIR}/bin/*.dll)
       install(FILES ${OPENSSL_DLL} DESTINATION ${INSTALL_RUNTIME_DIR})
     endif()
-  endif()
+endif()
 
   set(plugins "")
   foreach(plugin ${AvogadroLibs_PLUGINS})