diff --git a/src/CLASS2/improper_class2.cpp b/src/CLASS2/improper_class2.cpp
index fe2619d82c..152c29bfa3 100644
--- a/src/CLASS2/improper_class2.cpp
+++ b/src/CLASS2/improper_class2.cpp
@@ -702,8 +702,8 @@ void ImproperClass2::angleangle(int eflag, int vflag)
     thetaCBD = acos(costhCBD);
 
     dthABC = thetaABC - aa_theta0_1[type];
-    dthCBD = thetaCBD - aa_theta0_2[type];
-    dthABD = thetaABD - aa_theta0_3[type];
+    dthABD = thetaABD - aa_theta0_2[type];
+    dthCBD = thetaCBD - aa_theta0_3[type];
 
     // energy