diff --git a/ldms/src/core/ldms.c b/ldms/src/core/ldms.c
index c8611c7cd..5bb53262d 100644
--- a/ldms/src/core/ldms.c
+++ b/ldms/src/core/ldms.c
@@ -1579,18 +1579,39 @@ ldms_set_t ldms_set_create(const char *instance_name,
 	 */
 	const char *s = instance_name;
 	while (*s != '\0') {
+		/* Control characters are not allowed because they would confuse
+		 * parsing of set names
+		 */
 		if (iscntrl(*s)) {
 			errno = EINVAL;
 			return NULL;
 		}
+		/* Double-quote not allowed in quoted string because we
+		 * would have to add logic to handle "" vs. '' when encoding
+		 * as JSON
+		 */
 		if (*s == '"') {
 			errno = EINVAL;
 			return NULL;
 		}
+		/* Single-quote not allowed in quoted string because we
+		 * would have to add logic to handle "" vs. '' when encoding
+		 * as JSON
+		 */
 		if (*s == '\'') {
 			errno = EINVAL;
 			return NULL;
 		}
+		/* Backslash would hide intended character in encoded string */
+		if (*s == '\\') {
+			errno = EINVAL;
+			return NULL;
+		}
+		/* Character values above 127 are not allowed */
+		if (0 != (*s & ~0x7f)) {
+			errno = EINVAL;
+			return NULL;
+		}
 		s++;
 	}
 
diff --git a/ldms/src/core/ldms.h b/ldms/src/core/ldms.h
index fab1f3d57..41dc0295e 100644
--- a/ldms/src/core/ldms.h
+++ b/ldms/src/core/ldms.h
@@ -1618,9 +1618,13 @@ ldms_set_t ldms_set_new_with_auth(const char *instance_name,
 				  uid_t uid, gid_t gid, mode_t perm);
 
 /**
- * \brief Create an LDMS metric set with owner, permission, and heap size
+ * \brief Create an LDMS metric set
  *
- * Create a metric set, but with customized \c uid, \c gid, \c perm, and \c heap_sz
+ * Create a metric set, with \c uid, \c gid, \c perm, and \c heap_sz
+ * The \c instance name must be unique among sets in the application and must only
+ * contain the characters [a-z], [A-Z], [0-9] and [:-+/%&]. Note that the characters
+ * +, -, / and * are allowed for compatability reasons, but their use is discouraged
+ * in new code because they can be confused with mathematical operators.
  *
  * \param instance_name   The name of the metric set
  * \param schema          The schema of the set