diff --git a/devicemodel/core/mevent.c b/devicemodel/core/mevent.c
index 860e4f2b8..2c3a84886 100644
--- a/devicemodel/core/mevent.c
+++ b/devicemodel/core/mevent.c
@@ -30,7 +30,6 @@
  * Micro event library for FreeBSD, designed for a single i/o thread
  * using EPOLL, and having events be persistent by default.
  */
-#include <assert.h>
 #include <errno.h>
 #include <stdlib.h>
 #include <stdio.h>
@@ -377,7 +376,6 @@ int
 mevent_init(void)
 {
 	epoll_fd = epoll_create1(0);
-	assert(epoll_fd >= 0);
 
 	if (epoll_fd >= 0)
 		return 0;
@@ -420,7 +418,10 @@ mevent_dispatch(void)
 	 * Add internal event handler for the pipe write fd
 	 */
 	pipev = mevent_add(mevent_pipefd[0], EVF_READ, mevent_pipe_read, NULL, NULL, NULL);
-	assert(pipev != NULL);
+	if (!pipev) {
+		fprintf(stderr, "pipefd mevent_add failed\n");
+		exit(0);
+	}
 
 	for (;;) {
 		int suspend_mode;
diff --git a/devicemodel/hw/pci/uart.c b/devicemodel/hw/pci/uart.c
index cc76f4940..a0eee6460 100644
--- a/devicemodel/hw/pci/uart.c
+++ b/devicemodel/hw/pci/uart.c
@@ -60,22 +60,18 @@ static void
 pci_uart_write(struct vmctx *ctx, int vcpu, struct pci_vdev *dev,
 	       int baridx, uint64_t offset, int size, uint64_t value)
 {
-	assert(baridx == 0);
-	assert(size == 1);
-
-	uart_write(dev->arg, offset, value);
+	if (baridx == 0 && size == 1)
+		uart_write(dev->arg, offset, value);
 }
 
 uint64_t
 pci_uart_read(struct vmctx *ctx, int vcpu, struct pci_vdev *dev,
 	      int baridx, uint64_t offset, int size)
 {
-	uint8_t val;
+	uint8_t val = 0xff;
 
-	assert(baridx == 0);
-	assert(size == 1);
-
-	val = uart_read(dev->arg, offset);
+	if (baridx == 0 && size == 1)
+		val = uart_read(dev->arg, offset);
 	return val;
 }
 
diff --git a/devicemodel/hw/pci/virtio/virtio_console.c b/devicemodel/hw/pci/virtio/virtio_console.c
index 7369ca818..733b554ea 100644
--- a/devicemodel/hw/pci/virtio/virtio_console.c
+++ b/devicemodel/hw/pci/virtio/virtio_console.c
@@ -39,7 +39,6 @@
 #include <stdbool.h>
 #include <string.h>
 #include <unistd.h>
-#include <assert.h>
 #include <pthread.h>
 #include <termios.h>
 #include <limits.h>
@@ -272,15 +271,13 @@ virtio_console_add_port(struct virtio_console *console, const char *name,
 
 static void
 virtio_console_control_tx(struct virtio_console_port *port, void *arg,
-			  struct iovec *iov, int niov)
+			  struct iovec *iov, int niov __attribute__((unused)))
 {
 	struct virtio_console *console;
 	struct virtio_console_port *tmp;
 	struct virtio_console_control resp, *ctrl;
 	int i;
 
-	assert(niov == 1);
-
 	console = port->console;
 	ctrl = (struct virtio_console_control *)iov->iov_base;
 
@@ -363,8 +360,10 @@ virtio_console_control_send(struct virtio_console *console,
 		return;
 
 	n = vq_getchain(vq, &idx, &iov, 1, NULL);
-
-	assert(n == 1);
+	if (n < 1) {
+		WPRINTF(("vtcon: control_send vq_getchain error %d\n", n));
+		return;
+	}
 
 	memcpy(iov.iov_base, ctrl, sizeof(struct virtio_console_control));
 	if (payload != NULL && len > 0)
diff --git a/devicemodel/hw/uart_core.c b/devicemodel/hw/uart_core.c
index 002e3c90a..d2b6d5024 100644
--- a/devicemodel/hw/uart_core.c
+++ b/devicemodel/hw/uart_core.c
@@ -29,7 +29,6 @@
 
 #include <stdio.h>
 #include <stdlib.h>
-#include <assert.h>
 #include <fcntl.h>
 #include <termios.h>
 #include <unistd.h>
@@ -167,7 +166,9 @@ rxfifo_reset(struct uart_vdev *uart, int size)
 {
 	struct fifo *fifo;
 
-	assert(size <= uart->rxfifo_size);
+	if (size > uart->rxfifo_size)
+		size = uart->rxfifo_size;
+
 	fifo = &uart->rxfifo;
 	fifo->rindex = 0;
 	fifo->windex = 0;
@@ -301,7 +302,6 @@ modem_status(uint8_t mcr)
 		 */
 		msr = MSR_DCD | MSR_DSR;
 	}
-	assert((msr & MSR_DELTA_MASK) == 0);
 
 	return msr;
 }
@@ -373,8 +373,6 @@ uart_drain(int fd, enum ev_type ev, void *arg)
 
 	uart = arg;
 
-	assert(ev == EVF_READ);
-
 	/*
 	 * This routine is called in the context of the mevent thread
 	 * to take out the uart lock to protect against concurrent
@@ -632,18 +630,17 @@ uart_init(uart_intr_func_t intr_assert, uart_intr_func_t intr_deassert,
 	struct uart_vdev *uart;
 
 	uart = calloc(1, sizeof(struct uart_vdev) + rxfifo_size);
+	if (uart) {
+		uart->arg = arg;
+		uart->rxfifo_size = rxfifo_size;
+		uart->intr_assert = intr_assert;
+		uart->intr_deassert = intr_deassert;
+		uart->rxfifo.buf = (uint8_t *)(uart + 1);
 
-	assert(uart != NULL);
+		pthread_mutex_init(&uart->mtx, NULL);
 
-	uart->arg = arg;
-	uart->rxfifo_size = rxfifo_size;
-	uart->intr_assert = intr_assert;
-	uart->intr_deassert = intr_deassert;
-	uart->rxfifo.buf = (uint8_t *)(uart + 1);
-
-	pthread_mutex_init(&uart->mtx, NULL);
-
-	uart_reset(uart);
+		uart_reset(uart);
+	}
 
 	return uart;
 }