diff --git a/src/string_utils.c b/src/string_utils.c
index 46eddf06..3a8dac49 100644
--- a/src/string_utils.c
+++ b/src/string_utils.c
@@ -76,10 +76,24 @@ void string_upper(char *s) {
     for (; *s; ++s) *s = toupper(*s);
 }
 
+bool string_is_upper(char *s) {
+    for (; *s; ++s) {
+        if (*s != toupper(*s)) return false;
+    }
+    return true;
+}
+
 void string_lower(char *s) {
     for (; *s; ++s) *s = tolower(*s);
 }
 
+bool string_is_lower(char *s) {
+    for (; *s; ++s) {
+        if (*s != tolower(*s)) return false;
+    }
+    return true;
+}
+
 uint string_translate(char *str, size_t len, char *word_chars, char *word_repls, size_t trans_len) {
     uint num_replacements = 0;
     
diff --git a/src/string_utils.h b/src/string_utils.h
index 87595d90..bcf1ccec 100644
--- a/src/string_utils.h
+++ b/src/string_utils.h
@@ -37,8 +37,10 @@ int string_compare_len_case_insensitive(const char *str1, const char *str2, size
 size_t string_common_prefix(const char *str1, const char *str2);
 size_t string_common_suffix(const char *str1, const char *str2);
 
-void string_lower(char *str);
-void string_upper(char *str);
+bool string_is_lower(char *s);
+void string_lower(char *s);
+bool string_is_upper(char *s);
+void string_upper(char *s);
 
 bool string_starts_with(const char *str, const char *start);
 bool string_ends_with(const char *str, const char *ending);