--- a/src/utils/cst_tokenstream.c
+++ b/src/utils/cst_tokenstream.c
@@ -266,7 +266,7 @@ static void get_token_sub_part(cst_token
     (*buffer)[p] = '\0';
 }
 
-inline int ts_utf8_sequence_length(char c0)
+static inline int ts_utf8_sequence_length(char c0)
 {
     // Get the expected length of UTF8 sequence given its most
     // significant byte
--- a/src/utils/cst_val.c
+++ b/src/utils/cst_val.c
@@ -475,7 +475,7 @@ int val_dec_refcount(const cst_val *b)
     }
 }
 
-inline int utf8_sequence_length(char c0)
+static inline int utf8_sequence_length(char c0)
 {
     // Get the expected length of UTF8 sequence given its most
     // significant byte
