diff --git a/CMakeLists.txt b/CMakeLists.txt
index ea62bbceb0e..963601dd94a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -540,13 +540,19 @@ IF(WITH_BUILDINFO)
 	IF(UNIX)
 		EXEC_PROGRAM("date \"+%Y-%m-%d\"" OUTPUT_VARIABLE BUILD_DATE)
 		EXEC_PROGRAM("date \"+%H:%M:%S\"" OUTPUT_VARIABLE BUILD_TIME)  
-		EXEC_PROGRAM("svnversion ${CMAKE_SOURCE_DIR}" OUTPUT_VARIABLE BUILD_REV)
+		EXEC_PROGRAM("svnversion ${CMAKE_SOURCE_DIR}" OUTPUT_VARIABLE BUILD_REV RETURN_VALUE BUILD_REV_RETURN)
+		IF(BUILD_REV_RETURN)
+			SET(BUILD_REV "unknown")
+		ENDIF(BUILD_REV_RETURN)
 	ENDIF(UNIX)
 	
 	IF(WIN32)
 		EXEC_PROGRAM("cmd /c date /t" OUTPUT_VARIABLE BUILD_DATE)
 		EXEC_PROGRAM("cmd /c time /t" OUTPUT_VARIABLE BUILD_TIME)  
-		EXEC_PROGRAM("svnversion ${CMAKE_SOURCE_DIR}" OUTPUT_VARIABLE BUILD_REV)
+		EXEC_PROGRAM("svnversion ${CMAKE_SOURCE_DIR}" OUTPUT_VARIABLE BUILD_REV RETURN_VALUE BUILD_REV_RETURN)
+		IF(BUILD_REV_RETURN)
+			SET(BUILD_REV "unknown")
+		ENDIF(BUILD_REV_RETURN)
 	ENDIF(WIN32)
 ENDIF(WITH_BUILDINFO)