diff --git a/pppd/Makefile.linux b/pppd/Makefile.linux
index 9664f70..d07e01e 100644
--- a/pppd/Makefile.linux
+++ b/pppd/Makefile.linux
@@ -125,7 +125,7 @@ CFLAGS   += -DHAS_SHADOW
 #LIBS     += -lshadow $(LIBS)
 endif
 
-ifneq ($(wildcard $(shell $(CC) --print-sysroot)/usr/include/crypt.h),)
+ifneq ($(wildcard @glibc@/include/crypt.h),)
 CFLAGS  += -DHAVE_CRYPT_H=1
 LIBS   += -lcrypt
 endif
@@ -137,7 +137,7 @@ endif
 
 ifdef NEEDDES
 ifndef USE_CRYPT
-CFLAGS   += -I$(shell $(CC) --print-sysroot)/usr/include/openssl
+CFLAGS   += -I@openssl@/include/openssl
 LIBS     += -lcrypto
 else
 CFLAGS   += -DUSE_CRYPT=1
@@ -188,7 +188,7 @@ LIBS        += -ldl
 endif
 
 ifdef FILTER
-ifneq ($(wildcard /usr/include/pcap-bpf.h),)
+ifneq ($(wildcard @libpcap@/include/pcap-bpf.h),)
 LIBS    += -lpcap
 CFLAGS  += -DPPP_FILTER
 endif