diff --git a/src/ebusd/Makefile.am b/src/ebusd/Makefile.am
index 32be82f8..9e19b7c9 100644
--- a/src/ebusd/Makefile.am
+++ b/src/ebusd/Makefile.am
@@ -1,7 +1,6 @@
 AM_CXXFLAGS = -I$(top_srcdir)/src \
+	      -isystem$(top_srcdir) \
 	      -Wconversion -Wno-unused-parameter \
-	      -isystem$(top_srcdir)/src/lib/utils \
-	      -isystem$(top_srcdir)/src/lib/ebus \
 	      -DSYSCONFDIR=\"$(sysconfdir)\" \
 	      -DLOCALSTATEDIR=\"$(localstatedir)\"
 
diff --git a/src/lib/ebus/Makefile.am b/src/lib/ebus/Makefile.am
index 9a642d3b..d3691345 100644
--- a/src/lib/ebus/Makefile.am
+++ b/src/lib/ebus/Makefile.am
@@ -1,4 +1,5 @@
 AM_CXXFLAGS = -I$(top_srcdir)/src \
+	      -isystem$(top_srcdir) \
 	      -Wconversion -Wno-unused-parameter
 
 noinst_LIBRARIES = libebus.a
diff --git a/src/lib/ebus/contrib/Makefile.am b/src/lib/ebus/contrib/Makefile.am
index 0d4bac60..b5b79daa 100644
--- a/src/lib/ebus/contrib/Makefile.am
+++ b/src/lib/ebus/contrib/Makefile.am
@@ -1,5 +1,6 @@
 AM_CXXFLAGS = -I$(top_srcdir)/src \
-	-Wno-unused-parameter
+	      -isystem$(top_srcdir) \
+	      -Wno-unused-parameter
 
 noinst_LIBRARIES = libebuscontrib.a
 
diff --git a/src/lib/ebus/contrib/test/Makefile.am b/src/lib/ebus/contrib/test/Makefile.am
index 5c1056af..f79824cb 100644
--- a/src/lib/ebus/contrib/test/Makefile.am
+++ b/src/lib/ebus/contrib/test/Makefile.am
@@ -1,5 +1,6 @@
 AM_CXXFLAGS = -I$(top_srcdir)/src \
-	-Wno-unused-parameter
+	      -isystem$(top_srcdir) \
+	      -Wno-unused-parameter
 
 noinst_PROGRAMS = test_contrib
 
diff --git a/src/lib/ebus/test/Makefile.am b/src/lib/ebus/test/Makefile.am
index e626d51a..6058eb36 100644
--- a/src/lib/ebus/test/Makefile.am
+++ b/src/lib/ebus/test/Makefile.am
@@ -1,4 +1,5 @@
 AM_CXXFLAGS = -I$(top_srcdir)/src \
+	      -isystem$(top_srcdir) \
 	      -Wno-unused-parameter
 
 noinst_PROGRAMS = test_filereader \
diff --git a/src/lib/utils/Makefile.am b/src/lib/utils/Makefile.am
index 93f27feb..b6d0526a 100644
--- a/src/lib/utils/Makefile.am
+++ b/src/lib/utils/Makefile.am
@@ -1,4 +1,5 @@
 AM_CXXFLAGS = -I$(top_srcdir)/src \
+	      -isystem$(top_srcdir) \
 	      -Wconversion
 
 noinst_LIBRARIES = libutils.a
diff --git a/src/tools/Makefile.am b/src/tools/Makefile.am
index c9dc337e..a53a9cbd 100644
--- a/src/tools/Makefile.am
+++ b/src/tools/Makefile.am
@@ -1,4 +1,5 @@
-AM_CXXFLAGS = -I$(top_srcdir)/src
+AM_CXXFLAGS = -I$(top_srcdir)/src \
+	      -isystem$(top_srcdir)
 
 bin_PROGRAMS = ebusctl \
 	       ebusfeed
@@ -17,4 +18,3 @@ endif
 distclean-local:
 	-rm -f Makefile.in
 	-rm -rf .libs
-