diff --git a/Makefile.am b/Makefile.am
index 63cce5e3..c48a8915 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -119,6 +119,7 @@ rofi_CFLAGS=\
 	-DMANPAGE_PATH="\"$(mandir)/\""\
 	-I$(top_srcdir)/include/\
 	-I$(top_builddir)/lexer/\
+	-I$(top_srcdir)/lexer/\
 	-I$(top_srcdir)/config/\
 	-I$(top_builddir)/\
 	-Werror=missing-prototypes\
@@ -269,6 +270,7 @@ textbox_test_CFLAGS=\
 	-DTHEME_DIR=\"$(themedir)\"\
 	-I$(top_srcdir)/include/\
 	-I$(top_builddir)/lexer/\
+	-I$(top_srcdir)/lexer/\
 	-I$(top_srcdir)/config/\
 	-I$(top_builddir)/
 
@@ -415,6 +417,7 @@ helper_test_CFLAGS=\
 	-DTHEME_DIR=\"$(themedir)\"\
 	-I$(top_srcdir)/include/\
 	-I$(top_builddir)/lexer/\
+	-I$(top_srcdir)/lexer/\
 	-I$(top_srcdir)/config/\
 	-I$(top_builddir)/