diff --git a/dist/tpm2-abrmd.service.in b/dist/tpm2-abrmd.service.in
index b0b562ce..0effaa99 100644
--- a/dist/tpm2-abrmd.service.in
+++ b/dist/tpm2-abrmd.service.in
@@ -2,8 +2,9 @@
 Description=TPM2 Access Broker and Resource Management Daemon
 # These settings are needed when using the device TCTI. If the
 # TCP mssim is used then the settings should be commented out.
-After=dev-tpm0.device
-Requires=dev-tpm0.device
+After=dev-tpm0.device dev-tcm0.device
+ConditionPathExists=|/dev/tpm0
+ConditionPathExists=|/dev/tcm0
 
 [Service]
 Type=dbus
diff --git a/src/tabrmd-defaults.h b/src/tabrmd-defaults.h
index 7387a470..edb3cc0a 100644
--- a/src/tabrmd-defaults.h
+++ b/src/tabrmd-defaults.h
@@ -16,7 +16,7 @@
 #define TABRMD_ENTROPY_SRC_DEFAULT "/dev/urandom"
 #define TABRMD_SESSIONS_MAX_DEFAULT 4
 #define TABRMD_SESSIONS_MAX 64
-#define TABRMD_TCTI_CONF_DEFAULT "device:/dev/tpm0"
+#define TABRMD_TCTI_CONF_DEFAULT ((!access("/dev/tcm0", F_OK)) ? ("device:/dev/tcm0") : ("device:/dev/tpm0"))
 #define TABRMD_TRANSIENT_MAX_DEFAULT 27
 #define TABRMD_TRANSIENT_MAX 100