diff --git a/lib/Makefile.am b/lib/Makefile.am
index e873c8f3..637f4dee 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -25,7 +25,7 @@ noinst_LIBRARIES = libbison.a
 # config.h in build/., and system.h is in src/src/.
 INCLUDES = -I$(top_builddir)/intl \
            -I$(top_builddir)      \
-           -I$(top_srcdir)/ \
+           -I$(top_srcdir)/src \
            -I$(top_srcdir)/intl \
            -I$(top_srcdir)/lib