diff --git a/src/Base/Parser.sh b/src/Base/Parser.sh
index 601b395d3c..5d01ba19a9 100644
--- a/src/Base/Parser.sh
+++ b/src/Base/Parser.sh
@@ -3,6 +3,6 @@
 (cd "$(dirname "$0")" && \
   flex -oQuantity.lex.c Quantity.l && \
   bison -oQuantity.tab.c Quantity.y && \
-  sed -i '1s|^|// clang-format off\n|' Quantity.tab.c && \
-  sed -i '1s|^|// clang-format off\n|' Quantity.lex.c \
+  sed -i '1s|^|// SPDX-License-Identifier: LGPL-2.1-or-later\n\n// clang-format off\n|' Quantity.tab.c && \
+  sed -i '1s|^|// SPDX-License-Identifier: LGPL-2.1-or-later\n\n// clang-format off\n|' Quantity.lex.c \
 )