diff --git a/sys/arm/allwinner/a10_gpio.c b/sys/arm/allwinner/a10_gpio.c
index bc0d92a21b77..0ccea4fe1caf 100644
--- a/sys/arm/allwinner/a10_gpio.c
+++ b/sys/arm/allwinner/a10_gpio.c
@@ -300,8 +300,8 @@ a10_gpio_pin_setflags(device_t dev, uint32_t pin, uint32_t flags)
 	if (i >= sc->sc_gpio_npins)
 		return (EINVAL);
 
-	/* Filter out unwanted flags. */
-	if ((flags &= sc->sc_gpio_pins[i].gp_caps) != flags)
+	/* Check for unwanted flags. */
+	if ((flags & sc->sc_gpio_pins[i].gp_caps) != flags)
 		return (EINVAL);
 
 	/* Can't mix input/output together. */
diff --git a/sys/arm/broadcom/bcm2835/bcm2835_gpio.c b/sys/arm/broadcom/bcm2835/bcm2835_gpio.c
index 8029d8050f65..9ddb44b2a792 100644
--- a/sys/arm/broadcom/bcm2835/bcm2835_gpio.c
+++ b/sys/arm/broadcom/bcm2835/bcm2835_gpio.c
@@ -385,8 +385,8 @@ bcm_gpio_pin_setflags(device_t dev, uint32_t pin, uint32_t flags)
 	if (bcm_gpio_pin_is_ro(sc, pin))
 		return (EINVAL);
 
-	/* Filter out unwanted flags. */
-	if ((flags &= sc->sc_gpio_pins[i].gp_caps) != flags)
+	/* Check for unwanted flags. */
+	if ((flags & sc->sc_gpio_pins[i].gp_caps) != flags)
 		return (EINVAL);
 
 	/* Can't mix input/output together. */
diff --git a/sys/arm/freescale/imx/imx51_gpio.c b/sys/arm/freescale/imx/imx51_gpio.c
index d42a3135acbc..c23a49d3038f 100644
--- a/sys/arm/freescale/imx/imx51_gpio.c
+++ b/sys/arm/freescale/imx/imx51_gpio.c
@@ -261,8 +261,8 @@ imx51_gpio_pin_setflags(device_t dev, uint32_t pin, uint32_t flags)
 	if (i >= sc->gpio_npins)
 		return (EINVAL);
 
-	/* Filter out unwanted flags */
-	if ((flags &= sc->gpio_pins[i].gp_caps) != flags)
+	/* Check for unwanted flags. */
+	if ((flags & sc->gpio_pins[i].gp_caps) != flags)
 		return (EINVAL);
 
 	/* Can't mix input/output together */
diff --git a/sys/arm/xscale/ixp425/avila_gpio.c b/sys/arm/xscale/ixp425/avila_gpio.c
index dc4e33a9437f..8be99489507a 100644
--- a/sys/arm/xscale/ixp425/avila_gpio.c
+++ b/sys/arm/xscale/ixp425/avila_gpio.c
@@ -220,8 +220,8 @@ avila_gpio_pin_setflags(device_t dev, uint32_t pin, uint32_t flags)
 	if (pin >= IXP4XX_GPIO_PINS || !(sc->sc_valid & mask))
 		return (EINVAL);
 
-	/* Filter out unwanted flags */
-	if ((flags &= sc->sc_pins[pin].gp_caps) != flags)
+	/* Check for unwanted flags. */
+	if ((flags & sc->sc_pins[pin].gp_caps) != flags)
 		return (EINVAL);
 
 	/* Can't mix input/output together */
diff --git a/sys/arm/xscale/ixp425/cambria_gpio.c b/sys/arm/xscale/ixp425/cambria_gpio.c
index 34f5d214d1c0..18472cd41978 100644
--- a/sys/arm/xscale/ixp425/cambria_gpio.c
+++ b/sys/arm/xscale/ixp425/cambria_gpio.c
@@ -317,8 +317,8 @@ cambria_gpio_pin_setflags(device_t dev, uint32_t pin, uint32_t flags)
 	if (pin >= GPIO_PINS)
 		return (EINVAL);
 
-	/* Filter out unwanted flags */
-	if ((flags &= sc->sc_pins[pin].gp_caps) != flags)
+	/* Check for unwanted flags. */
+	if ((flags & sc->sc_pins[pin].gp_caps) != flags)
 		return (EINVAL);
 
 	/* Can't mix input/output together */
diff --git a/sys/mips/atheros/ar71xx_gpio.c b/sys/mips/atheros/ar71xx_gpio.c
index 23386e5b1890..580208eb7e1b 100644
--- a/sys/mips/atheros/ar71xx_gpio.c
+++ b/sys/mips/atheros/ar71xx_gpio.c
@@ -219,8 +219,8 @@ ar71xx_gpio_pin_setflags(device_t dev, uint32_t pin, uint32_t flags)
 	if (i >= sc->gpio_npins)
 		return (EINVAL);
 
-	/* Filter out unwanted flags */
-	if ((flags &= sc->gpio_pins[i].gp_caps) != flags)
+	/* Check for unwanted flags. */
+	if ((flags & sc->gpio_pins[i].gp_caps) != flags)
 		return (EINVAL);
 
 	/* Can't mix input/output together */
diff --git a/sys/mips/cavium/octeon_gpio.c b/sys/mips/cavium/octeon_gpio.c
index 96ce39caf634..788f0aa48a60 100644
--- a/sys/mips/cavium/octeon_gpio.c
+++ b/sys/mips/cavium/octeon_gpio.c
@@ -219,8 +219,8 @@ octeon_gpio_pin_setflags(device_t dev, uint32_t pin, uint32_t flags)
 	if (i >= sc->gpio_npins)
 		return (EINVAL);
 
-	/* Filter out unwanted flags */
-	if ((flags &= sc->gpio_pins[i].gp_caps) != flags)
+	/* Check for unwanted flags. */
+	if ((flags & sc->gpio_pins[i].gp_caps) != flags)
 		return (EINVAL);
 
 	/* Can't mix input/output together */
diff --git a/sys/mips/rt305x/rt305x_gpio.c b/sys/mips/rt305x/rt305x_gpio.c
index a911b3329175..1d685187ec17 100644
--- a/sys/mips/rt305x/rt305x_gpio.c
+++ b/sys/mips/rt305x/rt305x_gpio.c
@@ -242,8 +242,8 @@ rt305x_gpio_pin_setflags(device_t dev, uint32_t pin, uint32_t flags)
 	if (i >= sc->gpio_npins)
 		return (EINVAL);
 
-	/* Filter out unwanted flags */
-	if ((flags &= sc->gpio_pins[i].gp_caps) != flags)
+	/* Check for unwanted flags. */
+	if ((flags & sc->gpio_pins[i].gp_caps) != flags)
 		return (EINVAL);
 
 	/* Can't mix input/output together */