diff --git a/NEWS.md b/NEWS.md
index 5dbe9565..711dc612 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,5 +1,7 @@
 # clock (development version)
 
+* Avoid non-API `SET_ATTRIB()`.
+
 # clock 0.7.3
 
 * `%Y`, `%F`, `%G`, and `%c` now parse up to 4 _characters_ by default, rather
diff --git a/src/clock.h b/src/clock.h
index c64bf69f..6e4f04ab 100644
--- a/src/clock.h
+++ b/src/clock.h
@@ -29,4 +29,13 @@
 #define r_chr_na NA_STRING
 #define r_lgl_na NA_LOGICAL
 
+#if R_VERSION < R_Version(4, 5, 0)
+static inline
+void CLEAR_ATTRIB(SEXP x) {
+  SET_ATTRIB(x, R_NilValue);
+  SET_OBJECT(x, 0);
+  UNSET_S4_OBJECT(x);
+}
+#endif
+
 #endif
diff --git a/src/rcrd.cpp b/src/rcrd.cpp
index ca25ea8a..79058985 100644
--- a/src/rcrd.cpp
+++ b/src/rcrd.cpp
@@ -15,8 +15,8 @@ new_clock_rcrd_from_fields(SEXP fields, SEXP names, SEXP classes) {
 
   // Clear all attributes except for `names`, as we often
   // pass in other duration or time point objects as `fields`
-  SEXP field_names = Rf_getAttrib(fields, R_NamesSymbol);
-  SET_ATTRIB(fields, r_null);
+  SEXP field_names = PROTECT(Rf_getAttrib(fields, R_NamesSymbol));
+  CLEAR_ATTRIB(fields);
   Rf_setAttrib(fields, R_NamesSymbol, field_names);
 
   const r_ssize n_fields = Rf_xlength(fields);
@@ -54,7 +54,7 @@ new_clock_rcrd_from_fields(SEXP fields, SEXP names, SEXP classes) {
     SET_VECTOR_ELT(fields, 0, field0);
   }
 
-  UNPROTECT(1);
+  UNPROTECT(2);
   return fields;
 }