diff --git a/libs/libcodec2/src/Makefile.am b/libs/libcodec2/src/Makefile.am
index 8d0d990c43..5dae366d8b 100644
--- a/libs/libcodec2/src/Makefile.am
+++ b/libs/libcodec2/src/Makefile.am
@@ -3,7 +3,7 @@ AUTOMAKE_OPTS = gnu
 NAME = codec2
 AM_CPPFLAGS = $(AM_CFLAGS)
 
-D=codebook
+D=$(abs_srcdir)/codebook
 
 # lsp quantisers
 
diff --git a/libs/libcodec2/unittest/Makefile.am b/libs/libcodec2/unittest/Makefile.am
index df6e327261..9e3494895d 100644
--- a/libs/libcodec2/unittest/Makefile.am
+++ b/libs/libcodec2/unittest/Makefile.am
@@ -1,4 +1,4 @@
-AM_CFLAGS = -I../src -fPIC -g  -DFLOATING_POINT -DVAR_ARRAYS -O2 -Wall
+AM_CFLAGS = -I../src -I$(abs_srcdir)/../src -fPIC -g  -DFLOATING_POINT -DVAR_ARRAYS -O2 -Wall
 AUTOMAKE_OPTS = gnu
 NAME = libcodec2
 AM_CPPFLAGS = $(AM_CFLAGS)
diff --git a/src/mod/codecs/mod_codec2/Makefile.am b/src/mod/codecs/mod_codec2/Makefile.am
index 9c6bb6a397..878157e9a8 100644
--- a/src/mod/codecs/mod_codec2/Makefile.am
+++ b/src/mod/codecs/mod_codec2/Makefile.am
@@ -7,7 +7,7 @@ CODEC2LA=$(CODEC2_BUILDDIR)/src/libcodec2.la
 
 mod_LTLIBRARIES = mod_codec2.la
 mod_codec2_la_SOURCES  = mod_codec2.c
-mod_codec2_la_CFLAGS   = $(AM_CFLAGS) -I$(CODEC2_DIR)/include -I$(CODEC2_BUILDDIR)/src
+mod_codec2_la_CFLAGS   = $(AM_CFLAGS) -I$(CODEC2_DIR)/include -I$(CODEC2_BUILDDIR)/src -I$(CODEC2_DIR)/src
 mod_codec2_la_LIBADD   = $(switch_builddir)/libfreeswitch.la $(CODEC2LA)
 mod_codec2_la_LDFLAGS  = -avoid-version -module -no-undefined -shared