diff --git a/src/tex2lyx/table.cpp b/src/tex2lyx/table.cpp
index dddf71df6a..c5a1d716eb 100644
--- a/src/tex2lyx/table.cpp
+++ b/src/tex2lyx/table.cpp
@@ -85,14 +85,15 @@ public:
 };
 
 
+/// the numeric values are part of the file format!
 enum Multicolumn {
 	/// A normal cell
 	CELL_NORMAL = 0,
 	/// A multicolumn cell. The number of columns is <tt>1 + number
 	/// of CELL_PART_OF_MULTICOLUMN cells</tt> that follow directly
-	CELL_BEGIN_OF_MULTICOLUMN,
+	CELL_BEGIN_OF_MULTICOLUMN = 1,
 	/// This is a dummy cell (part of a multicolumn cell)
-	CELL_PART_OF_MULTICOLUMN
+	CELL_PART_OF_MULTICOLUMN = 2
 };
 
 
diff --git a/src/tex2lyx/tex2lyx.h b/src/tex2lyx/tex2lyx.h
index 9085bf33e7..f87f767239 100644
--- a/src/tex2lyx/tex2lyx.h
+++ b/src/tex2lyx/tex2lyx.h
@@ -114,7 +114,7 @@ extern CommandMap known_math_environments;
 ///
 extern bool noweb_mode;
 /// LyX format that is created by tex2lyx
-int const LYX_FORMAT = 276;
+int const LYX_FORMAT = 277;
 
 /// path of the master .tex file
 extern std::string getMasterFilePath();