diff --git a/libutils/include/utils/cbor64.h b/libutils/include/utils/cbor64.h
index 148daad..96fd002 100644
--- a/libutils/include/utils/cbor64.h
+++ b/libutils/include/utils/cbor64.h
@@ -417,9 +417,9 @@
 /* Tracks the strings which have already been emitted and their index. */
 typedef struct {
     char **strings;
-    size_t emitted;
     /* Use shared values rather than string references */
     bool shared_values;
+    uint64_t emitted;
 } cbor64_domain_t;
 
 /* Start a new domain with no inner string references */
diff --git a/libutils/src/cbor64.c b/libutils/src/cbor64.c
index def52c4..06f54a2 100644
--- a/libutils/src/cbor64.c
+++ b/libutils/src/cbor64.c
@@ -158,7 +158,7 @@
      * encoding, don't actually track the string in the references.
      */
     size_t length = strlen(domain->strings[index]);
-    size_t next_ref = domain->emitted;
+    uint64_t next_ref = domain->emitted;
 
     bool is_referenced = true;
     if (next_ref < 24) {