diff --git a/doc/sphinx/arm/hooks.rst b/doc/sphinx/arm/hooks.rst
index 2c8e048bed..0eb2f56824 100644
--- a/doc/sphinx/arm/hooks.rst
+++ b/doc/sphinx/arm/hooks.rst
@@ -619,7 +619,7 @@ Where:
 -  relay-info - for relayed packets the giaddr and the RAI circuit-id,
    remote-id, and subscriber-id options (option 82 sub options: 1, 2 and
    6) if present. The circuit id and remote id are presented as hex
-   strings and when printable with their content.
+   strings. When their content is printable it is displayed.
 
 -  user-context - the optional user context associated with the lease.
 
diff --git a/src/lib/util/strutil.h b/src/lib/util/strutil.h
index 16d0ceed19..5a3a6c5e9c 100644
--- a/src/lib/util/strutil.h
+++ b/src/lib/util/strutil.h
@@ -344,9 +344,8 @@ typedef boost::shared_ptr<StringSanitizer> StringSanitizerPtr;
 /// \param content String to check for printable characters
 /// \return True if empty or contains only printable characters, False otherwise
 inline bool
-isPrintable(const std::string& content)
-{
-    for (const unsigned char& ch : content) {
+isPrintable(const std::string& content) {
+    for (const auto& ch : content) {
         if (isprint(ch) == 0) {
             return (false);
         }
@@ -359,9 +358,8 @@ isPrintable(const std::string& content)
 /// \param content Vector to check for printable characters
 /// \return True if empty or contains only printable characters, False otherwise
 inline bool
-isPrintable(const std::vector<uint8_t>& content)
-{
-    for (const unsigned char& ch : content) {
+isPrintable(const std::vector<uint8_t>& content) {
+    for (const auto& ch : content) {
         if (isprint(ch) == 0) {
             return (false);
         }