diff --git a/components/battery.c b/components/battery.c
index 49f43e6..807a7e6 100644
--- a/components/battery.c
+++ b/components/battery.c
@@ -59,13 +59,12 @@
 
 		fd = open("/dev/apm", O_RDONLY);
 		if (fd < 0) {
-			fprintf(stderr, "open '/dev/apm': %s\n", strerror(errno));
+			warn("open '/dev/apm':");
 			return NULL;
 		}
 
 		if (ioctl(fd, APM_IOC_GETPOWER, &apm_info) < 0) {
-			fprintf(stderr, "ioctl 'APM_IOC_GETPOWER': %s\n",
-			        strerror(errno));
+			warn("ioctl 'APM_IOC_GETPOWER':");
 			close(fd);
 			return NULL;
 		}
@@ -90,13 +89,12 @@
 
 		fd = open("/dev/apm", O_RDONLY);
 		if (fd < 0) {
-			fprintf(stderr, "open '/dev/apm': %s\n", strerror(errno));
+			warn("open '/dev/apm':");
 			return NULL;
 		}
 
 		if (ioctl(fd, APM_IOC_GETPOWER, &apm_info) < 0) {
-			fprintf(stderr, "ioctl 'APM_IOC_GETPOWER': %s\n",
-			        strerror(errno));
+			warn("ioctl 'APM_IOC_GETPOWER':");
 			close(fd);
 			return NULL;
 		}
diff --git a/components/cpu.c b/components/cpu.c
index 02e7671..b9b3924 100644
--- a/components/cpu.c
+++ b/components/cpu.c
@@ -57,7 +57,7 @@
 		size = sizeof(freq);
 
 		if (sysctl(mib, 2, &freq, &size, NULL, 0) < 0) {
-			fprintf(stderr, "sysctl 'HW_CPUSPEED': %s\n", strerror(errno));
+			warn("sysctl 'HW_CPUSPEED':");
 			return NULL;
 		}
 
@@ -80,7 +80,7 @@
 
 		memcpy(b, a, sizeof(b));
 		if (sysctl(mib, 2, &a, &size, NULL, 0) < 0) {
-			fprintf(stderr, "sysctl 'KERN_CPTIME': %s\n", strerror(errno));
+			warn("sysctl 'KERN_CPTIME':");
 			return NULL;
 		}
 		if (!valid) {
diff --git a/components/datetime.c b/components/datetime.c
index 12d7717..c3efae3 100644
--- a/components/datetime.c
+++ b/components/datetime.c
@@ -11,7 +11,7 @@ datetime(const char *fmt)
 
 	t = time(NULL);
 	if (!strftime(buf, sizeof(buf), fmt, localtime(&t))) {
-		fprintf(stderr, "strftime: Result string exceeds buffer size\n");
+		warn("strftime: Result string exceeds buffer size");
 		return NULL;
 	}
 
diff --git a/components/disk.c b/components/disk.c
index bf69875..f4031ea 100644
--- a/components/disk.c
+++ b/components/disk.c
@@ -12,7 +12,7 @@ disk_free(const char *mnt)
 	struct statvfs fs;
 
 	if (statvfs(mnt, &fs) < 0) {
-		fprintf(stderr, "statvfs '%s': %s\n", mnt, strerror(errno));
+		warn("statvfs '%s':", mnt);
 		return NULL;
 	}
 
@@ -26,7 +26,7 @@ disk_perc(const char *mnt)
 	struct statvfs fs;
 
 	if (statvfs(mnt, &fs) < 0) {
-		fprintf(stderr, "statvfs '%s': %s\n", mnt, strerror(errno));
+		warn("statvfs '%s':", mnt);
 		return NULL;
 	}
 
@@ -40,7 +40,7 @@ disk_total(const char *mnt)
 	struct statvfs fs;
 
 	if (statvfs(mnt, &fs) < 0) {
-		fprintf(stderr, "statvfs '%s': %s\n", mnt, strerror(errno));
+		warn("statvfs '%s':", mnt);
 		return NULL;
 	}
 
@@ -54,7 +54,7 @@ disk_used(const char *mnt)
 	struct statvfs fs;
 
 	if (statvfs(mnt, &fs) < 0) {
-		fprintf(stderr, "statvfs '%s': %s\n", mnt, strerror(errno));
+		warn("statvfs '%s':", mnt);
 		return NULL;
 	}
 
diff --git a/components/hostname.c b/components/hostname.c
index d41465f..dc3bbf1 100644
--- a/components/hostname.c
+++ b/components/hostname.c
@@ -10,7 +10,7 @@ const char *
 hostname(void)
 {
 	if (gethostname(buf, sizeof(buf)) < 0) {
-		fprintf(stderr, "gethostbyname: %s\n", strerror(errno));
+		warn("gethostbyname:");
 		return NULL;
 	}
 
diff --git a/components/ip.c b/components/ip.c
index 85ac15e..fce2b66 100644
--- a/components/ip.c
+++ b/components/ip.c
@@ -19,7 +19,7 @@ ipv4(const char *iface)
 	char host[NI_MAXHOST];
 
 	if (getifaddrs(&ifaddr) < 0) {
-		fprintf(stderr, "getifaddrs: %s\n", strerror(errno));
+		warn("getifaddrs:");
 		return NULL;
 	}
 
@@ -32,7 +32,7 @@ ipv4(const char *iface)
 		if (!strcmp(ifa->ifa_name, iface) &&
 		    (ifa->ifa_addr->sa_family == AF_INET)) {
 			if (s != 0) {
-				fprintf(stderr, "getnameinfo: %s\n", gai_strerror(s));
+				warn("getnameinfo: %s", gai_strerror(s));
 				return NULL;
 			}
 			return bprintf("%s", host);
@@ -52,7 +52,7 @@ ipv6(const char *iface)
 	char host[NI_MAXHOST];
 
 	if (getifaddrs(&ifaddr) < 0) {
-		fprintf(stderr, "getifaddrs: %s\n", strerror(errno));
+		warn("getifaddrs:");
 		return NULL;
 	}
 
@@ -65,7 +65,7 @@ ipv6(const char *iface)
 		if (!strcmp(ifa->ifa_name, iface) &&
 		    (ifa->ifa_addr->sa_family == AF_INET6)) {
 			if (s != 0) {
-				fprintf(stderr, "getnameinfo: %s\n", gai_strerror(s));
+				warn("getnameinfo: %s", gai_strerror(s));
 				return NULL;
 			}
 			return bprintf("%s", host);
diff --git a/components/kernel_release.c b/components/kernel_release.c
index 4e67a28..531014c 100644
--- a/components/kernel_release.c
+++ b/components/kernel_release.c
@@ -12,7 +12,7 @@ kernel_release(void)
 	struct utsname udata;
 
 	if (uname(&udata) < 0) {
-		fprintf(stderr, "uname: %s\n", strerror(errno));
+		warn("uname:");
 		return NULL;
 	}
 
diff --git a/components/keyboard_indicators.c b/components/keyboard_indicators.c
index 2f831c8..73ba32e 100644
--- a/components/keyboard_indicators.c
+++ b/components/keyboard_indicators.c
@@ -11,7 +11,7 @@ keyboard_indicators(void)
 	XKeyboardState state;
 
 	if (!(dpy = XOpenDisplay(NULL))) {
-		fprintf(stderr, "Cannot open display\n");
+		warn("XOpenDisplay: Failed to open display");
 		return NULL;
 	}
 	XGetKeyboardControl(dpy, &state);
diff --git a/components/load_avg.c b/components/load_avg.c
index 526dc71..ea7bc2c 100644
--- a/components/load_avg.c
+++ b/components/load_avg.c
@@ -10,7 +10,7 @@ load_avg(const char *fmt)
 	double avgs[3];
 
 	if (getloadavg(avgs, 3) < 0) {
-		fprintf(stderr, "getloadavg: Could not obtain load average.\n");
+		warn("getloadavg: Failed to obtain load average");
 		return NULL;
 	}
 
diff --git a/components/num_files.c b/components/num_files.c
index 327a64d..9179037 100644
--- a/components/num_files.c
+++ b/components/num_files.c
@@ -14,7 +14,7 @@ num_files(const char *dir)
 	int num;
 
 	if (!(fd = opendir(dir))) {
-		fprintf(stderr, "opendir '%s': %s\n", dir, strerror(errno));
+		warn("opendir '%s':", dir);
 		return NULL;
 	}
 
diff --git a/components/run_command.c b/components/run_command.c
index 1aaae20..b5eeff0 100644
--- a/components/run_command.c
+++ b/components/run_command.c
@@ -12,7 +12,7 @@ run_command(const char *cmd)
 	FILE *fp;
 
 	if (!(fp = popen(cmd, "r"))) {
-		fprintf(stderr, "popen '%s': %s\n", cmd, strerror(errno));
+		warn("popen '%s':", cmd);
 		return NULL;
 	}
 	p = fgets(buf, sizeof(buf) - 1, fp);
diff --git a/components/swap.c b/components/swap.c
index caa4788..234e7d1 100644
--- a/components/swap.c
+++ b/components/swap.c
@@ -13,11 +13,11 @@
 		size_t bytes_read;
 
 		if (!(fp = fopen(path, "r"))) {
-			fprintf(stderr, "fopen '%s': %s\n", path, strerror(errno));
+			warn("fopen '%s':", path);
 			return 0;
 		}
 		if (!(bytes_read = fread(buf, sizeof(char), bufsiz, fp))) {
-			fprintf(stderr, "fread '%s': %s\n", path, strerror(errno));
+			warn("fread '%s':", path);
 			fclose(fp);
 			return 0;
 		}
@@ -139,21 +139,21 @@
 
 		nswap = swapctl(SWAP_NSWAP, 0, 0);
 		if (nswap < 1) {
-			fprintf(stderr, "swaptctl 'SWAP_NSWAP': %s\n", strerror(errno));
+			warn("swaptctl 'SWAP_NSWAP':");
 		}
 
 		fsep = sep = calloc(nswap, sizeof(*sep));
 		if (!sep) {
-			fprintf(stderr, "calloc 'nswap': %s\n", strerror(errno));
+			warn("calloc 'nswap':");
 		}
 
 		rnswap = swapctl(SWAP_STATS, (void *)sep, nswap);
 		if (rnswap < 0) {
-			fprintf(stderr, "swapctl 'SWAP_STATA': %s\n", strerror(errno));
+			warn("swapctl 'SWAP_STATA':");
 		}
 
 		if (nswap != rnswap) {
-			fprintf(stderr, "SWAP_STATS != SWAP_NSWAP\n");
+			warn("getstats: SWAP_STATS != SWAP_NSWAP");
 		}
 
 		*total = 0;
diff --git a/components/temperature.c b/components/temperature.c
index 812ae77..64199f5 100644
--- a/components/temperature.c
+++ b/components/temperature.c
@@ -36,8 +36,7 @@
 		size = sizeof(temp);
 
 		if (sysctl(mib, 5, &temp, &size, NULL, 0) < 0) {
-			fprintf(stderr, "sysctl 'SENSOR_TEMP': %s\n",
-			        strerror(errno));
+			warn("sysctl 'SENSOR_TEMP':");
 			return NULL;
 		}
 
diff --git a/components/uptime.c b/components/uptime.c
index 981f3cd..45e12db 100644
--- a/components/uptime.c
+++ b/components/uptime.c
@@ -50,7 +50,7 @@ format(int uptime)
 		size = sizeof(boottime);
 
 		if (sysctl(mib, 2, &boottime, &size, NULL, 0) < 0) {
-			fprintf(stderr, "sysctl 'KERN_BOOTTIME': %s\n", strerror(errno));
+			warn("sysctl 'KERN_BOOTTIME':");
 			return NULL;
 		}
 
diff --git a/components/user.c b/components/user.c
index 8ab6db9..cd503f6 100644
--- a/components/user.c
+++ b/components/user.c
@@ -20,7 +20,7 @@ username(void)
 	struct passwd *pw;
 
 	if (!(pw = getpwuid(geteuid()))) {
-		fprintf(stderr, "getpwuid '%d': %s\n", geteuid(), strerror(errno));
+		warn("getpwuid '%d':", geteuid());
 		return NULL;
 	}
 
diff --git a/components/volume.c b/components/volume.c
index aa46446..8674211 100644
--- a/components/volume.c
+++ b/components/volume.c
@@ -21,21 +21,19 @@ vol_perc(const char *card)
 	char *vnames[] = SOUND_DEVICE_NAMES;
 
 	if ((afd = open(card, O_RDONLY | O_NONBLOCK)) < 0) {
-		fprintf(stderr, "open '%s': %s\n", card, strerror(errno));
+		warn("open '%s':", card);
 		return NULL;
 	}
 
 	if (ioctl(afd, (int)SOUND_MIXER_READ_DEVMASK, &devmask) < 0) {
-		fprintf(stderr, "ioctl 'SOUND_MIXER_READ_DEVMASK': %s\n",
-		        strerror(errno));
+		warn("ioctl 'SOUND_MIXER_READ_DEVMASK':");
 		close(afd);
 		return NULL;
 	}
 	for (i = 0; i < LEN(vnames); i++) {
 		if (devmask & (1 << i) && !strcmp("vol", vnames[i])) {
 			if (ioctl(afd, MIXER_READ(i), &v) < 0) {
-				fprintf(stderr, "ioctl 'MIXER_READ(%ld)': %s\n", i,
-				        strerror(errno));
+				warn("ioctl 'MIXER_READ(%ld)':", i);
 				close(afd);
 				return NULL;
 			}
diff --git a/components/wifi.c b/components/wifi.c
index 414d533..591f6ad 100644
--- a/components/wifi.c
+++ b/components/wifi.c
@@ -26,8 +26,7 @@
 		snprintf(path, sizeof(path), "%s%s%s", "/sys/class/net/", iface,
 		         "/operstate");
 		if (!(fp = fopen(path, "r"))) {
-			fprintf(stderr, "fopen '%s': %s\n", path,
-			        strerror(errno));
+			warn("fopen '%s':", path);
 			return NULL;
 		}
 		p = fgets(status, 5, fp);
@@ -37,8 +36,7 @@
 		}
 
 		if (!(fp = fopen("/proc/net/wireless", "r"))) {
-			fprintf(stderr, "fopen '/proc/net/wireless': %s\n",
-			        strerror(errno));
+			warn("fopen '/proc/net/wireless':");
 			return NULL;
 		}
 
@@ -74,13 +72,12 @@
 		snprintf(wreq.ifr_name, sizeof(wreq.ifr_name), "%s", iface);
 
 		if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
-			fprintf(stderr, "socket 'AF_INET': %s\n",
-			        strerror(errno));
+			warn("socket 'AF_INET':");
 			return NULL;
 		}
 		wreq.u.essid.pointer = id;
 		if (ioctl(sockfd,SIOCGIWESSID, &wreq) < 0) {
-			fprintf(stderr, "ioctl 'SIOCGIWESSID': %s\n", strerror(errno));
+			warn("ioctl 'SIOCGIWESSID':");
 			close(sockfd);
 			return NULL;
 		}
@@ -111,22 +108,19 @@
 		memset(&bssid, 0, sizeof(bssid));
 		memset(nr, 0, sizeof(struct ieee80211_nodereq));
 		if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
-			fprintf(stderr, "socket 'AF_INET': %s\n",
-				strerror(errno));
+			warn("socket 'AF_INET':");
 			return 0;
 		}
 		strlcpy(bssid.i_name, iface, sizeof(bssid.i_name));
 		if ((ioctl(sockfd, SIOCG80211BSSID, &bssid)) < 0) {
-			fprintf(stderr, "ioctl 'SIOCG80211BSSID': %s\n",
-				strerror(errno));
+			warn("ioctl 'SIOCG80211BSSID':");
 			close(sockfd);
 			return 0;
 		}
 		strlcpy(nr->nr_ifname, iface, sizeof(nr->nr_ifname));
 		memcpy(&nr->nr_macaddr, bssid.i_bssid, sizeof(nr->nr_macaddr));
 		if ((ioctl(sockfd, SIOCG80211NODE, nr)) < 0 && nr->nr_rssi) {
-			fprintf(stderr, "ioctl 'SIOCG80211NODE': %s\n",
-				strerror(errno));
+			warn("ioctl 'SIOCG80211NODE':");
 			close(sockfd);
 			return 0;
 		}
diff --git a/slstatus.c b/slstatus.c
index 7ff323f..0c4605f 100644
--- a/slstatus.c
+++ b/slstatus.c
@@ -17,7 +17,6 @@ struct arg {
 	const char *args;
 };
 
-char *argv0;
 char buf[1024];
 static int done;
 static Display *dpy;
@@ -43,8 +42,7 @@ difftimespec(struct timespec *res, struct timespec *a, struct timespec *b)
 static void
 usage(void)
 {
-	fprintf(stderr, "usage: %s [-s]\n", argv0);
-	exit(1);
+	die("usage: %s [-s]", argv0);
 }
 
 int
@@ -80,14 +78,12 @@ main(int argc, char *argv[])
 	}
 
 	if (!sflag && !(dpy = XOpenDisplay(NULL))) {
-		fprintf(stderr, "XOpenDisplay: Failed to open display\n");
-		return 1;
+		die("XOpenDisplay: Failed to open display");
 	}
 
 	while (!done) {
 		if (clock_gettime(CLOCK_MONOTONIC, &start) < 0) {
-			fprintf(stderr, "clock_gettime: %s\n", strerror(errno));
-			return 1;
+			die("clock_gettime:");
 		}
 
 		status[0] = '\0';
@@ -97,11 +93,10 @@ main(int argc, char *argv[])
 			}
 			if ((ret = snprintf(status + len, sizeof(status) - len,
 			                    args[i].fmt, res)) < 0) {
-				fprintf(stderr, "snprintf: %s\n",
-				        strerror(errno));
+				warn("snprintf:");
 				break;
 			} else if ((size_t)ret >= sizeof(status) - len) {
-				fprintf(stderr, "snprintf: Output truncated\n");
+				warn("snprintf: Output truncated");
 				break;
 			}
 			len += ret;
@@ -111,18 +106,14 @@ main(int argc, char *argv[])
 			printf("%s\n", status);
 		} else {
 			if (XStoreName(dpy, DefaultRootWindow(dpy), status) < 0) {
-				fprintf(stderr,
-				        "XStoreName: Allocation failed\n");
-				return 1;
+				die("XStoreName: Allocation failed");
 			}
 			XFlush(dpy);
 		}
 
 		if (!done) {
 			if (clock_gettime(CLOCK_MONOTONIC, &current) < 0) {
-				fprintf(stderr, "clock_gettime: %s\n",
-				        strerror(errno));
-				return 1;
+				die("clock_gettime:");
 			}
 			difftimespec(&diff, &current, &start);
 
@@ -133,9 +124,7 @@ main(int argc, char *argv[])
 			if (wait.tv_sec >= 0) {
 				if (nanosleep(&wait, NULL) < 0 &&
 				    errno != EINTR) {
-					fprintf(stderr, "nanosleep: %s\n",
-					        strerror(errno));
-					return 1;
+					die("nanosleep:");
 				}
 			}
 		}
@@ -144,9 +133,7 @@ main(int argc, char *argv[])
 	if (!sflag) {
 		XStoreName(dpy, DefaultRootWindow(dpy), NULL);
 		if (XCloseDisplay(dpy) < 0) {
-			fprintf(stderr,
-			        "XCloseDisplay: Failed to close display\n");
-			return 1;
+			die("XCloseDisplay: Failed to close display");
 		}
 	}
 
diff --git a/util.c b/util.c
index 6113049..08f14ff 100644
--- a/util.c
+++ b/util.c
@@ -2,10 +2,52 @@
 #include <errno.h>
 #include <stdarg.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 
 #include "util.h"
 
+char *argv0;
+
+static void
+verr(const char *fmt, va_list ap)
+{
+	if (argv0 && strncmp(fmt, "usage", sizeof("usage") - 1)) {
+		fprintf(stderr, "%s: ", argv0);
+	}
+
+	vfprintf(stderr, fmt, ap);
+
+	if (fmt[0] && fmt[strlen(fmt) - 1] == ':') {
+		fputc(' ', stderr);
+		perror(NULL);
+	} else {
+		fputc('\n', stderr);
+	}
+}
+
+void
+warn(const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	verr(fmt, ap);
+	va_end(ap);
+}
+
+void
+die(const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	verr(fmt, ap);
+	va_end(ap);
+
+	exit(1);
+}
+
 const char *
 bprintf(const char *fmt, ...)
 {
@@ -14,9 +56,9 @@ bprintf(const char *fmt, ...)
 
 	va_start(ap, fmt);
 	if ((ret = vsnprintf(buf, sizeof(buf), fmt, ap)) < 0) {
-		fprintf(stderr, "vsnprintf: %s\n", strerror(errno));
+		warn("vsnprintf:");
 	} else if ((size_t)ret >= sizeof(buf)) {
-		fprintf(stderr, "vsnprintf: Output truncated\n");
+		warn("vsnprintf: Output truncated");
 	}
 	va_end(ap);
 
@@ -31,7 +73,7 @@ pscanf(const char *path, const char *fmt, ...)
 	int n;
 
 	if (!(fp = fopen(path, "r"))) {
-		fprintf(stderr, "fopen '%s': %s\n", path, strerror(errno));
+		warn("fopen '%s':", path);
 		return -1;
 	}
 	va_start(ap, fmt);
diff --git a/util.h b/util.h
index e90c29d..a73b103 100644
--- a/util.h
+++ b/util.h
@@ -3,5 +3,10 @@ extern char buf[1024];
 
 #define LEN(x) (sizeof (x) / sizeof *(x))
 
+extern char *argv0;
+
+void warn(const char *, ...);
+void die(const char *, ...);
+
 const char *bprintf(const char *fmt, ...);
 int pscanf(const char *path, const char *fmt, ...);