diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index 2a0376a..05f6a81 100644
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -1463,7 +1463,7 @@
 	}
 
 	if (round_str == NULL) {
-		round_str = PyUnicode_FromString("__round__");
+		round_str = PyUnicode_InternFromString("__round__");
 		if (round_str == NULL)
 			return NULL;
 	}
@@ -1582,7 +1582,7 @@
 	}
 
 	if (trunc_str == NULL) {
-		trunc_str = PyUnicode_FromString("__trunc__");
+		trunc_str = PyUnicode_InternFromString("__trunc__");
 		if (trunc_str == NULL)
 			return NULL;
 	}