diff --git a/cpu/sam0_common/periph/spi.c b/cpu/sam0_common/periph/spi.c
index 7cf29e46a5..52158da6b0 100644
--- a/cpu/sam0_common/periph/spi.c
+++ b/cpu/sam0_common/periph/spi.c
@@ -350,13 +350,15 @@ void spi_init(spi_t bus)
 void spi_init_pins(spi_t bus)
 {
     /* MISO must always have PD/PU, see #5968. This is a ~65uA difference */
-    gpio_init(spi_config[bus].miso_pin, GPIO_IN_PD);
+    if (gpio_is_valid(spi_config[bus].miso_pin)) {
+        gpio_init(spi_config[bus].miso_pin, GPIO_IN_PD);
+        gpio_init_mux(spi_config[bus].miso_pin, spi_config[bus].miso_mux);
+    }
+
     gpio_init(spi_config[bus].mosi_pin, GPIO_OUT);
     gpio_init(spi_config[bus].clk_pin, GPIO_OUT);
-    gpio_init_mux(spi_config[bus].miso_pin, spi_config[bus].miso_mux);
-    gpio_init_mux(spi_config[bus].mosi_pin, spi_config[bus].mosi_mux);
-    /* clk_pin will be muxed during acquire / release */
 
+    /* mosi_pin, clk_pin will be muxed during acquire / release */
     mutex_unlock(&locks[bus]);
 }
 
@@ -364,8 +366,9 @@ void spi_deinit_pins(spi_t bus)
 {
     mutex_lock(&locks[bus]);
 
-    gpio_disable_mux(spi_config[bus].miso_pin);
-    gpio_disable_mux(spi_config[bus].mosi_pin);
+    if (gpio_is_valid(spi_config[bus].miso_pin)) {
+        gpio_disable_mux(spi_config[bus].miso_pin);
+    }
 }
 
 int spi_acquire(spi_t bus, spi_cs_t cs, spi_mode_t mode, spi_clk_t clk)
@@ -385,6 +388,7 @@ int spi_acquire(spi_t bus, spi_cs_t cs, spi_mode_t mode, spi_clk_t clk)
     }
 
     /* mux clk_pin to SPI peripheral */
+    gpio_init_mux(spi_config[bus].mosi_pin, spi_config[bus].mosi_mux);
     gpio_init_mux(spi_config[bus].clk_pin, spi_config[bus].clk_mux);
 
     return SPI_OK;
@@ -392,9 +396,11 @@ int spi_acquire(spi_t bus, spi_cs_t cs, spi_mode_t mode, spi_clk_t clk)
 
 void spi_release(spi_t bus)
 {
-    /* Demux clk_pin back to GPIO_OUT function. Otherwise it will get HIGH-Z
-     * and lead to unexpected current draw by SPI salves. */
+    /* Demux clk_pin and mosi_pin back to GPIO_OUT function.
+     * Otherwise it will get HIGH-Z and lead to unexpected current draw by SPI salves.
+     */
     gpio_disable_mux(spi_config[bus].clk_pin);
+    gpio_disable_mux(spi_config[bus].mosi_pin);
 
     if (_is_qspi(bus)) {
         _qspi_release();