diff --git a/debian/libclang1-X.Y.symbols.in b/debian/libclang1-X.Y.symbols.in
index ef4669b0..e600dd43 100644
--- a/debian/libclang1-X.Y.symbols.in
+++ b/debian/libclang1-X.Y.symbols.in
@@ -1,5 +1,5 @@
 libclang-@LLVM_VERSION@.so.1 libclang1-@LLVM_VERSION@ #MINVER#
- LLVM_@LLVM_VERSION@@LLVM_@LLVM_VERSION@ 4.0
+ (optional)LLVM_@LLVM_VERSION@@LLVM_@LLVM_VERSION@ 4.0
  clang_BlockCommandComment_getArgText@LLVM_@LLVM_VERSION@ 3.2
  clang_BlockCommandComment_getCommandName@LLVM_@LLVM_VERSION@ 3.2
  clang_BlockCommandComment_getNumArgs@LLVM_@LLVM_VERSION@ 3.2