Index: head/sys/dev/ofw/openfirmio.h
===================================================================
--- head/sys/dev/ofw/openfirmio.h
+++ head/sys/dev/ofw/openfirmio.h
@@ -76,4 +76,18 @@
 /* Maximum accepted value length (maximum of nvramrc property). */
 #define	OFIOCMAXVALUE	8192
 
+/*
+ * While IEEE 1275-1994 states in 3.2.2.1.1 that property names are 1-31
+ * printable characters, in practice, this limit has been ignored.
+ * Noncompliant properties have been codified in standards such as LoPAPR.
+ *
+ * This is a suggested buffer length that should be large enough to hold
+ * any property name currently seen in device trees, without being overly
+ * wasteful of memory.
+ *
+ * If a future version of the Devicetree specification updates the property
+ * names length requirement, this value will be updated to match.
+ */
+#define	OFIOCSUGGPROPNAMELEN	64
+
 #endif /* _DEV_OFW_OPENFIRMIO_H_ */
Index: head/sys/dev/ofw/openfirmio.c
===================================================================
--- head/sys/dev/ofw/openfirmio.c
+++ head/sys/dev/ofw/openfirmio.c
@@ -115,7 +115,7 @@
 	phandle_t node;
 	int len, ok, error;
 	char *name, *value;
-	char newname[32];
+	char newname[OFIOCSUGGPROPNAMELEN];
 
 	if ((flags & FREAD) == 0)
 		return (EBADF);
@@ -222,8 +222,19 @@
 			break;
 		}
 		len = strlen(newname) + 1;
-		if (len > of->of_buflen)
+		if (len > of->of_buflen) {
+			/*
+			 * Passed buffer was insufficient.
+			 *
+			 * Instead of returning an error here, truncate the
+			 * property name to fit the buffer.
+			 *
+			 * This allows us to retain compatibility with old
+			 * tools which always pass a 32 character buffer.
+			 */
 			len = of->of_buflen;
+			newname[len - 1] = '\0';
+		}
 		else
 			of->of_buflen = len;
 		error = copyout(newname, of->of_buf, len);
Index: head/usr.sbin/ofwdump/ofwdump.c
===================================================================
--- head/usr.sbin/ofwdump/ofwdump.c
+++ head/usr.sbin/ofwdump/ofwdump.c
@@ -144,7 +144,7 @@
 ofw_dump_properties(int fd, phandle_t n, int level, int raw, int str)
 {
 	int nlen;
-	char prop[32];
+	char prop[OFIOCSUGGPROPNAMELEN];
 
 	for (nlen = ofw_firstprop(fd, n, prop, sizeof(prop)); nlen != 0;
 	     nlen = ofw_nextprop(fd, n, prop, prop, sizeof(prop)))