diff --git a/src/libexpr/Makefile.am b/src/libexpr/Makefile.am
index a16cd0785f..02269bcb8c 100644
--- a/src/libexpr/Makefile.am
+++ b/src/libexpr/Makefile.am
@@ -2,7 +2,9 @@ noinst_LIBRARIES = libexpr.a
 
 libexpr_a_SOURCES = nixexpr.cc nixexpr.hh parser.cc parser.hh \
  eval.cc eval.hh primops.cc primops.hh \
- lexer.l lexer-tab.c lexer-tab.h parser.y parser-tab.c parser-tab.h
+ lexer-tab.c lexer-tab.h parser-tab.c parser-tab.h
+
+EXTRA_DIST = lexer.l parser.y
 
 AM_CXXFLAGS = \
  -I.. -I../../externals/inst/include -I../libutil -I../libstore