diff --git a/doc/src/fix_adapt.rst b/doc/src/fix_adapt.rst
index ed611b2c7c..8fb103f5c6 100644
--- a/doc/src/fix_adapt.rst
+++ b/doc/src/fix_adapt.rst
@@ -457,21 +457,23 @@ all types from 1 to :math:`N`.  A leading asterisk means all types from
 If :doc:`dihedral_style hybrid <dihedral_hybrid>` is used, *dstyle* should be a
 sub-style name. The dihedral styles that currently work with fix adapt are:
 
-+------------------------------------------------------------------------+----------------+----------------+
-| :doc:`charmm  <dihedral_charmm>`                                       | k,n,d          | type dihedrals |
-+------------------------------------------------------------------------+----------------+----------------+
-| :doc:`charmmfsw <dihedral_charmm>`                                     | k,n,d          | type dihedrals |
-+------------------------------------------------------------------------+----------------+----------------+
-| :doc:`cosine/squared/restricted <dihedral_cosine_squared_restricted>`  | k,phi0         | type dihedrals |
-+------------------------------------------------------------------------+----------------+----------------+
-| :doc:`helix <dihedral_helix>`                                          | a,b,c          | type dihedrals |
-+------------------------------------------------------------------------+----------------+----------------+
-| :doc:`multi/harmonic <dihedral_multi_harmonic>`                        | a1,a2,a3,a4,a5 | type dihedrals |
-+------------------------------------------------------------------------+----------------+----------------+
-| :doc:`opls <dihedral_opls>`                                            | k1,k2,k3,k4    | type dihedrals |
-+------------------------------------------------------------------------+----------------+----------------+
-| :doc:`quadratic <dihedral_quadratic>`                                  | k,phi0         | type dihedrals |
-+------------------------------------------------------------------------+----------------+----------------+
++------------------------------------------------------------------------+-------------------------+----------------+
+| :doc:`charmm  <dihedral_charmm>`                                       | k,n,d                   | type dihedrals |
++------------------------------------------------------------------------+-------------------------+----------------+
+| :doc:`charmmfsw <dihedral_charmm>`                                     | k,n,d                   | type dihedrals |
++------------------------------------------------------------------------+-------------------------+----------------+
+| :doc:`class2 <dihedral_class2>`                                        | k1,k2,k3,phi1,phi2,phi3 | type dihedrals |
++------------------------------------------------------------------------+-------------------------+----------------+
+| :doc:`cosine/squared/restricted <dihedral_cosine_squared_restricted>`  | k,phi0                  | type dihedrals |
++------------------------------------------------------------------------+-------------------------+----------------+
+| :doc:`helix <dihedral_helix>`                                          | a,b,c                   | type dihedrals |
++------------------------------------------------------------------------+-------------------------+----------------+
+| :doc:`multi/harmonic <dihedral_multi_harmonic>`                        | a1,a2,a3,a4,a5          | type dihedrals |
++------------------------------------------------------------------------+-------------------------+----------------+
+| :doc:`opls <dihedral_opls>`                                            | k1,k2,k3,k4             | type dihedrals |
++------------------------------------------------------------------------+-------------------------+----------------+
+| :doc:`quadratic <dihedral_quadratic>`                                  | k,phi0                  | type dihedrals |
++------------------------------------------------------------------------+-------------------------+----------------+
 
 Note that internally, phi0 is stored in radians, so the variable
 this fix use to reset phi0 needs to generate values in radians.
diff --git a/src/CLASS2/dihedral_class2.cpp b/src/CLASS2/dihedral_class2.cpp
index 9c4c1ad871..3ca8c52717 100644
--- a/src/CLASS2/dihedral_class2.cpp
+++ b/src/CLASS2/dihedral_class2.cpp
@@ -946,3 +946,18 @@ void DihedralClass2::write_data(FILE *fp)
             at_theta0_1[i]*180.0/MY_PI,at_theta0_2[i]*180.0/MY_PI);
 }
 
+/* ----------------------------------------------------------------------
+    return ptr to internal members upon request
+ ------------------------------------------------------------------------ */
+
+ void *DihedralClass2::extract(const char *str, int &dim)
+ {
+   dim = 1;
+   if (strcmp(str, "k1") == 0) return (void *) k1;
+   if (strcmp(str, "k2") == 0) return (void *) k2;
+   if (strcmp(str, "k3") == 0) return (void *) k3;
+   if (strcmp(str, "phi1") == 0) return (void *) phi1;
+   if (strcmp(str, "phi2") == 0) return (void *) phi2;
+   if (strcmp(str, "phi3") == 0) return (void *) phi3;
+   return nullptr;
+ }
diff --git a/src/CLASS2/dihedral_class2.h b/src/CLASS2/dihedral_class2.h
index ad42c5c3a1..d87dfb8a7b 100644
--- a/src/CLASS2/dihedral_class2.h
+++ b/src/CLASS2/dihedral_class2.h
@@ -33,6 +33,7 @@ class DihedralClass2 : public Dihedral {
   void write_restart(FILE *) override;
   void read_restart(FILE *) override;
   void write_data(FILE *) override;
+  void *extract(const char *, int &) override;
 
  protected:
   double *k1, *k2, *k3;
diff --git a/unittest/force-styles/tests/dihedral-class2.yaml b/unittest/force-styles/tests/dihedral-class2.yaml
index b041d4ebcb..572bc4e5d8 100644
--- a/unittest/force-styles/tests/dihedral-class2.yaml
+++ b/unittest/force-styles/tests/dihedral-class2.yaml
@@ -17,7 +17,13 @@ dihedral_coeff: ! |
   *  at   75 42 31 75 42 31 120 50
   *  aat  75 120 160
   *  bb13 75 1.4 1.4
-extract: ! ""
+extract: ! |
+  k1 1
+  k2 1
+  k3 1
+  phi1 1
+  phi2 1
+  phi3 1
 natoms: 29
 init_energy: 3355.0074717375933
 init_stress: ! |2-