diff --git a/cpu/lpc2387/periph/spi.c b/cpu/lpc2387/periph/spi.c
index fecfc04d7cabf59f45a02ddb03fb6c97fa86c7ff..d7dae92eff6e35492cd83d7ca3713cadc20c8190 100644
--- a/cpu/lpc2387/periph/spi.c
+++ b/cpu/lpc2387/periph/spi.c
@@ -139,7 +139,7 @@ int spi_init_slave(spi_t dev, spi_conf_t conf, char (*cb)(char))
     (void)cb;
     printf("%s:%s(): stub\n", RIOT_FILE_RELATIVE, __func__);
     /* TODO */
-    return 0;
+    return -1;
 }
 
 void spi_transmission_begin(spi_t dev, char reset_val)
diff --git a/cpu/samd21/periph/spi.c b/cpu/samd21/periph/spi.c
index a7fe85a801ddce28e09bd42c85e3b8f766c2f805..69c680a78ff5774100868f32caf5e445dfd70040 100644
--- a/cpu/samd21/periph/spi.c
+++ b/cpu/samd21/periph/spi.c
@@ -200,7 +200,7 @@ int spi_init_master(spi_t dev, spi_conf_t conf, spi_speed_t speed)
 int spi_init_slave(spi_t dev, spi_conf_t conf, char (*cb)(char))
 {
     /* TODO */
-    return 0;
+    return -1;
 }
 
 void spi_transmission_begin(spi_t dev, char reset_val)
diff --git a/cpu/saml21/periph/spi.c b/cpu/saml21/periph/spi.c
index 8789c31c2b36fb5fd870eaed7c9bd7f018b95fde..c32e2f31296412275aa529978444fa7cd2f3a511 100644
--- a/cpu/saml21/periph/spi.c
+++ b/cpu/saml21/periph/spi.c
@@ -173,7 +173,7 @@ int spi_init_master(spi_t dev, spi_conf_t conf, spi_speed_t speed)
 int spi_init_slave(spi_t dev, spi_conf_t conf, char (*cb)(char))
 {
     /* TODO */
-    return 0;
+    return -1;
 }
 
 void spi_transmission_begin(spi_t dev, char reset_val)