diff --git a/bin/chcp.c b/bin/chcp.c
index 837cf01..8596a14 100644
--- a/bin/chcp.c
+++ b/bin/chcp.c
@@ -139,7 +139,8 @@ int main(int argc, char *argv[])
 
 	nilfs = nilfs_open(dev, NULL, NILFS_OPEN_RDWR | NILFS_OPEN_GCLK);
 	if (nilfs == NULL) {
-		fprintf(stderr, "%s: %s: cannot open NILFS\n", progname, dev);
+		fprintf(stderr, "%s: cannot open NILFS on %s: %m\n",
+			progname, dev ? : "device");
 		exit(1);
 	}
 
diff --git a/bin/dumpseg.c b/bin/dumpseg.c
index 24a3624..0c138b2 100644
--- a/bin/dumpseg.c
+++ b/bin/dumpseg.c
@@ -218,7 +218,8 @@ int main(int argc, char *argv[])
 
 	nilfs = nilfs_open(dev, NULL, NILFS_OPEN_RAW);
 	if (nilfs == NULL) {
-		fprintf(stderr, "%s: %s: cannot open NILFS\n", progname, dev);
+		fprintf(stderr, "%s: cannot open NILFS on %s: %m\n",
+			progname, dev ? : "device");
 		exit(1);
 	}
 
diff --git a/bin/lscp.c b/bin/lscp.c
index 52447e5..2de81b6 100644
--- a/bin/lscp.c
+++ b/bin/lscp.c
@@ -401,8 +401,8 @@ int main(int argc, char *argv[])
 
 	nilfs = nilfs_open(dev, NULL, NILFS_OPEN_RDONLY);
 	if (nilfs == NULL) {
-		fprintf(stderr, "%s: %s: cannot open NILFS\n",
-			progname, dev);
+		fprintf(stderr, "%s: cannot open NILFS on %s: %m\n",
+			progname, dev ? : "device");
 		exit(EXIT_FAILURE);
 	}
 
diff --git a/bin/lssu.c b/bin/lssu.c
index ebbd926..09ed973 100644
--- a/bin/lssu.c
+++ b/bin/lssu.c
@@ -382,8 +382,8 @@ int main(int argc, char *argv[])
 
 	nilfs = nilfs_open(dev, NULL, open_flags);
 	if (nilfs == NULL) {
-		fprintf(stderr, "%s: %s: cannot open NILFS\n",
-			progname, dev);
+		fprintf(stderr, "%s: cannot open NILFS on %s: %m\n",
+			progname, dev ? : "device");
 		exit(1);
 	}
 
diff --git a/bin/mkcp.c b/bin/mkcp.c
index 57cf0c8..9dd6f0e 100644
--- a/bin/mkcp.c
+++ b/bin/mkcp.c
@@ -123,7 +123,8 @@ int main(int argc, char *argv[])
 
 	nilfs = nilfs_open(dev, NULL, NILFS_OPEN_RDWR | NILFS_OPEN_GCLK);
 	if (nilfs == NULL) {
-		fprintf(stderr, "%s: %s: cannot open NILFS\n", progname, dev);
+		fprintf(stderr, "%s: cannot open NILFS on %s: %m\n",
+			progname, dev ? : "device");
 		exit(1);
 	}
 
diff --git a/bin/rmcp.c b/bin/rmcp.c
index 92d672f..0943fe0 100644
--- a/bin/rmcp.c
+++ b/bin/rmcp.c
@@ -193,7 +193,8 @@ int main(int argc, char *argv[])
 
 	nilfs = nilfs_open(dev, NULL, NILFS_OPEN_RDWR);
 	if (nilfs == NULL) {
-		fprintf(stderr, "%s: %s: cannot open NILFS\n", progname, dev);
+		fprintf(stderr, "%s: cannot open NILFS on %s: %m\n",
+			progname, dev ? : "device");
 		exit(1);
 	}