diff --git a/dlib/Makefile.am b/dlib/Makefile.am
index 378cd785..a45d6a57 100644
--- a/dlib/Makefile.am
+++ b/dlib/Makefile.am
@@ -1,3 +1,6 @@
+AM_CPPFLAGS = \
+	-I$(top_srcdir)
+
 noinst_LIBRARIES = libDlib.a
 
 libDlib_a_SOURCES = \
diff --git a/dpi/Makefile.am b/dpi/Makefile.am
index 3e47b9f3..ade14854 100644
--- a/dpi/Makefile.am
+++ b/dpi/Makefile.am
@@ -1,3 +1,6 @@
+AM_CPPFLAGS = \
+	-I$(top_srcdir)
+
 bookmarksdir = $(libdir)/dillo/dpi/bookmarks
 downloadsdir = $(libdir)/dillo/dpi/downloads
 ftpdir = $(libdir)/dillo/dpi/ftp
diff --git a/dpid/Makefile.am b/dpid/Makefile.am
index 07e262c8..a59fa083 100644
--- a/dpid/Makefile.am
+++ b/dpid/Makefile.am
@@ -1,4 +1,6 @@
-AM_CPPFLAGS=-DDPIDRC_SYS='"$(sysconfdir)/dpidrc"'
+AM_CPPFLAGS = \
+	-I$(top_srcdir) \
+	-DDPIDRC_SYS='"$(sysconfdir)/dpidrc"'
 
 bin_PROGRAMS = dpid dpidc
 dpid_LDADD = \
diff --git a/dpip/Makefile.am b/dpip/Makefile.am
index 099ac7d4..e88da0a1 100644
--- a/dpip/Makefile.am
+++ b/dpip/Makefile.am
@@ -1,3 +1,6 @@
+AM_CPPFLAGS = \
+	-I$(top_srcdir)
+
 noinst_LIBRARIES = libDpip.a
 
 libDpip_a_SOURCES = \
diff --git a/dw/Makefile.am b/dw/Makefile.am
index 7150fce9..3014b35d 100644
--- a/dw/Makefile.am
+++ b/dw/Makefile.am
@@ -1,3 +1,6 @@
+AM_CPPFLAGS = \
+	-I$(top_srcdir)
+
 noinst_LIBRARIES = \
 	libDw-core.a \
 	libDw-fltk.a \
diff --git a/lout/Makefile.am b/lout/Makefile.am
index 5a246708..a3f947db 100644
--- a/lout/Makefile.am
+++ b/lout/Makefile.am
@@ -1,3 +1,6 @@
+AM_CPPFLAGS = \
+	-I$(top_srcdir)
+
 noinst_LIBRARIES = liblout.a
 
 liblout_a_SOURCES = \
diff --git a/src/IO/Makefile.am b/src/IO/Makefile.am
index b168073c..c889dae8 100644
--- a/src/IO/Makefile.am
+++ b/src/IO/Makefile.am
@@ -1,4 +1,6 @@
-AM_CPPFLAGS=-DDILLO_BINDIR='"$(bindir)/"'
+AM_CPPFLAGS = \
+	-I$(top_srcdir) \
+	-DDILLO_BINDIR='"$(bindir)/"'
 AM_CFLAGS = @LIBFLTK_CFLAGS@
 AM_CXXFLAGS = @LIBFLTK_CXXFLAGS@
 
diff --git a/test/Makefile.am b/test/Makefile.am
index 5f24654c..a0a23c6a 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -1,3 +1,5 @@
+AM_CPPFLAGS = \
+	-I$(top_srcdir)
 AM_CFLAGS = @LIBFLTK_CFLAGS@
 AM_CXXFLAGS = @LIBFLTK_CXXFLAGS@