diff --git a/cpu/lpc2387/periph/spi.c b/cpu/lpc2387/periph/spi.c
index eef2621aa04b1ed012d7d5548c3f8ddf9a459186..03d07de635ccc70887c409e57a3a6bdfbe47d090 100644
--- a/cpu/lpc2387/periph/spi.c
+++ b/cpu/lpc2387/periph/spi.c
@@ -141,7 +141,7 @@ 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 1193de8e1c7706a16d1b037ee8f807bb924254ba..55973feb6a9b1f838c5d6486450f19ea1db9e4ae 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 0f9e7f73780d117ab2e1418d147d4ec8904393f0..e8d3730510ea30d9adbcc6665e9fec5878bd8a96 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)