diff --git a/gtk/Makefile.am b/gtk/Makefile.am
index 9163992c1c..cb4b6ca5ca 100644
--- a/gtk/Makefile.am
+++ b/gtk/Makefile.am
@@ -146,7 +146,8 @@ EXTRA_DIST = \
 	win32-file-dlg.h
 
 # Common headers
-AM_CPPFLAGS = -I$(top_srcdir) -I$(top_srcdir)/wiretap $(LIBGCRYPT_CFLAGS)
+AM_CPPFLAGS = -I$(top_srcdir) -I$(top_srcdir)/wiretap $(LIBGCRYPT_CFLAGS) $(PORTAUDIO_INCLUDES)
+
 
 doxygen:
 if HAVE_DOXYGEN