--- a/cmake/ecbuild_append_to_rpath.cmake
+++ b/cmake/ecbuild_append_to_rpath.cmake
@@ -31,7 +31,7 @@ function( _path_append var path )
 	else()
 		list( FIND ${var} ${path} _found )
 		if( _found EQUAL "-1" )
-			set( ${var} "${${var}}:${path}" PARENT_SCOPE )
+			set( ${var} "${${var}};${path}" PARENT_SCOPE )
 		endif()
 	endif()
 endfunction()