diff --git a/src/pam_panic/Makefile.am b/src/pam_panic/Makefile.am
index ab3c7e8..32ff1d2 100644
--- a/src/pam_panic/Makefile.am
+++ b/src/pam_panic/Makefile.am
@@ -3,7 +3,7 @@ SUBDIRS = man
 securelibdir = $(SECUREDIR)
 securelibexecdir = $(securelibdir)
 
-AM_CFLAGS = -DLOCALEDIR='"$(localedir)"'
+AM_CPPFLAGS = -DLOCALEDIR='"$(localedir)"'
 
 securelibexec_LTLIBRARIES = pam_panic.la
 pam_panic_la_SOURCES = \
diff --git a/src/pam_panic_pw/Makefile.am b/src/pam_panic_pw/Makefile.am
index 911e3a9..4f9c323 100644
--- a/src/pam_panic_pw/Makefile.am
+++ b/src/pam_panic_pw/Makefile.am
@@ -1,6 +1,6 @@
 SUBDIRS = man
 
-AM_CFLAGS = -DLOCALEDIR='"$(localedir)"'
+AM_CPPFLAGS = -DLOCALEDIR='"$(localedir)"'
 
 bin_PROGRAMS = pam_panic_pw
 pam_panic_pw_SOURCES = pam_panic_pw.c pam_panic_pw.h
diff --git a/test/Makefile.am b/test/Makefile.am
index 8b7587a..18626a1 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -1,4 +1,4 @@
-AM_CFLAGS = -DTEST
+AM_CPPFLAGS = -DTEST
 bin_PROGRAMS = test
 test_SOURCES = ../src/pam_panic/pam_panic_authdevice.c ../src/pam_panic/pam_panic_reject.c ../src/pam_panic_pw/pam_panic_pw.c test.c
 test_LDFLAGS = -lpam -lcrypt -lcunit