diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8edde739..9b9cfc0a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -25,12 +25,18 @@ set (CMAKE_LIBRARY_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/lib")
 #
 # Version
 #
-# TODO: Eliminate variables not prefixed with SYNERGY_
-if (DEFINED ENV{SYNERGY_VERSION_MAJOR})
-    set (VERSION_MAJOR $ENV{SYNERGY_VERSION_MAJOR})
-    set (VERSION_MINOR $ENV{SYNERGY_VERSION_MINOR})
-    set (VERSION_REV $ENV{SYNERGY_VERSION_PATCH})
-    set (VERSION_STAGE $ENV{SYNERGY_VERSION_STAGE})
+if ((NOT DEFINED SYNERGY_VERSION_MAJOR) AND (DEFINED ENV{SYNERGY_VERSION_MAJOR}))
+    set (SYNERGY_VERSION_MAJOR $ENV{SYNERGY_VERSION_MAJOR})
+    set (SYNERGY_VERSION_MINOR $ENV{SYNERGY_VERSION_MINOR})
+    set (SYNERGY_VERSION_PATCH $ENV{SYNERGY_VERSION_PATCH})
+    set (SYNERGY_VERSION_STAGE $ENV{SYNERGY_VERSION_STAGE})
+endif()
+
+if (DEFINED SYNERGY_VERSION_MAJOR)
+    set (VERSION_MAJOR ${SYNERGY_VERSION_MAJOR})
+    set (VERSION_MINOR ${SYNERGY_VERSION_MINOR})
+    set (VERSION_REV ${SYNERGY_VERSION_PATCH})
+    set (VERSION_STAGE ${SYNERGY_VERSION_STAGE})
 else()
     message (WARNING "Synergy version number not set by build environment.")
     set (VERSION_MAJOR 1)