diff --git a/include/openmc/constants.h b/include/openmc/constants.h
index 9c9a5f9b3..32cd8186a 100644
--- a/include/openmc/constants.h
+++ b/include/openmc/constants.h
@@ -319,7 +319,8 @@ enum class Interpolation {
   lin_log = 3,
   log_lin = 4,
   log_log = 5,
-  cubic = 6
+  quadratic = 6,
+  cubic = 7
 };
 
 enum class RunMode {
diff --git a/openmc/data/function.py b/openmc/data/function.py
index f03319eed..59f549d6f 100644
--- a/openmc/data/function.py
+++ b/openmc/data/function.py
@@ -13,7 +13,7 @@ from openmc.mixin import EqualityMixin
 from .data import EV_PER_MEV
 
 INTERPOLATION_SCHEME = {1: 'histogram', 2: 'linear-linear', 3: 'linear-log',
-                        4: 'log-linear', 5: 'log-log', 6 : 'cubic'}
+                        4: 'log-linear', 5: 'log-log', 6 : 'quadratic', 7 : 'cubic'}
 
 
 def sum_functions(funcs):