diff --git a/jv.c b/jv.c
index 92c48604..a1e98026 100644
--- a/jv.c
+++ b/jv.c
@@ -658,7 +658,7 @@ jv jv_string_append_buf(jv a, const char* buf, int len) {
   return a;
 }
 
-jv jv_string_append_codepoint(jv a, int c) {
+jv jv_string_append_codepoint(jv a, uint32_t c) {
   char buf[5];
   int len = jvp_utf8_encode(c, buf);
   jvp_string_append(&a.val.nontrivial, buf, len);
diff --git a/jv.h b/jv.h
index 50efbe60..a0bc3d4b 100644
--- a/jv.h
+++ b/jv.h
@@ -1,6 +1,8 @@
 #ifndef JV_H
 #define JV_H
 
+#include <stdint.h>
+
 typedef enum {
   JV_KIND_INVALID,
   JV_KIND_NULL,
@@ -82,7 +84,7 @@ unsigned long jv_string_hash(jv);
 const char* jv_string_value(jv);
 jv jv_string_concat(jv, jv);
 jv jv_string_fmt(const char*, ...);
-jv jv_string_append_codepoint(jv a, int c);
+jv jv_string_append_codepoint(jv a, uint32_t c);
 jv jv_string_append_buf(jv a, const char* buf, int len);
 jv jv_string_append_str(jv a, const char* str);
 jv jv_string_explode(jv j);