diff --git a/unittest/commands/test_variables.cpp b/unittest/commands/test_variables.cpp
index 7a9b87fbe2..c631b69528 100644
--- a/unittest/commands/test_variables.cpp
+++ b/unittest/commands/test_variables.cpp
@@ -780,6 +780,25 @@ TEST_F(VariableTest, Format)
     //    TEST_FAILURE(".*ERROR: Incorrect conversion in format string.*",
     //                 command("print \"${f1idx}\""););
 }
+
+TEST_F(VariableTest, Set)
+{
+    BEGIN_HIDE_OUTPUT();
+    command("variable three  string    three");
+    command("variable ten    internal  10.0");
+    END_HIDE_OUTPUT();
+    ASSERT_EQ(variable->nvar, 3);
+    ASSERT_THAT(variable->retrieve("three"), StrEq("three"));
+    ASSERT_THAT(variable->retrieve("ten"), StrEq("10"));
+
+    ASSERT_EQ(variable->internalstyle(variable->find("three")), 0);
+    ASSERT_EQ(variable->internalstyle(variable->find("ten")), 1);
+
+    variable->set_string("three", "new");
+    ASSERT_THAT(variable->retrieve("three"), StrEq("new"));
+    variable->internal_set(variable->find("ten"), -2.5);
+    ASSERT_THAT(variable->retrieve("ten"), StrEq("-2.5"));
+}
 } // namespace LAMMPS_NS
 
 int main(int argc, char **argv)
diff --git a/unittest/fortran/test_fortran_extract_variable.f90 b/unittest/fortran/test_fortran_extract_variable.f90
index b4b5ab8727..619962daf9 100644
--- a/unittest/fortran/test_fortran_extract_variable.f90
+++ b/unittest/fortran/test_fortran_extract_variable.f90
@@ -361,15 +361,23 @@ FUNCTION f_lammps_extract_variable_vector(i) BIND(C)
   f_lammps_extract_variable_vector = vector(i)
 END FUNCTION f_lammps_extract_variable_vector
 
-SUBROUTINE f_lammps_set_variable_string() BIND(C)
-  USE, INTRINSIC :: ISO_C_BINDING, ONLY : c_double, c_int
+SUBROUTINE f_lammps_set_string_variable() BIND(C)
   USE LIBLAMMPS
   USE keepstuff, ONLY : lmp, f2c_string
   IMPLICIT NONE
   CHARACTER(LEN=40) :: string
 
   string = "this is the new string"
-  CALL lmp%set_variable('str', string)
-END SUBROUTINE f_lammps_set_variable_string
+  CALL lmp%set_string_variable('str', string)
+END SUBROUTINE f_lammps_set_string_variable
+
+SUBROUTINE f_lammps_set_internal_variable() BIND(C)
+  USE, INTRINSIC :: ISO_C_BINDING, ONLY : c_double
+  USE LIBLAMMPS
+  USE keepstuff, ONLY : lmp, f2c_string
+  IMPLICIT NONE
+
+  CALL lmp%set_internal_variable('int', -2.5_c_double)
+END SUBROUTINE f_lammps_set_internal_variable
 
 ! vim: sts=2 ts=2 sw=2 et
diff --git a/unittest/fortran/wrap_extract_variable.cpp b/unittest/fortran/wrap_extract_variable.cpp
index 8c81897c0a..b1f79e149a 100644
--- a/unittest/fortran/wrap_extract_variable.cpp
+++ b/unittest/fortran/wrap_extract_variable.cpp
@@ -43,7 +43,9 @@ double f_lammps_extract_variable_internal();
 double f_lammps_extract_variable_equal();
 double f_lammps_extract_variable_atom(int);
 double f_lammps_extract_variable_vector(int);
-void f_lammps_set_variable_string();
+void f_lammps_set_string_variable();
+void f_lammps_set_internal_variable();
+
 char *c_path_join(const char *, const char *);
 }
 
@@ -155,7 +157,7 @@ TEST_F(LAMMPS_extract_variable, string)
     char *fstr = f_lammps_extract_variable_string();
     EXPECT_STREQ(fstr, "this is a string");
     std::free(fstr);
-    f_lammps_set_variable_string();
+    f_lammps_set_string_variable();
     fstr = f_lammps_extract_variable_string();
     EXPECT_STREQ(fstr, "this is the new string");
     std::free(fstr);
@@ -254,6 +256,8 @@ TEST_F(LAMMPS_extract_variable, internal)
 {
     f_lammps_setup_extract_variable();
     EXPECT_DOUBLE_EQ(f_lammps_extract_variable_internal(), 4.0);
+    f_lammps_set_internal_variable();
+    EXPECT_DOUBLE_EQ(f_lammps_extract_variable_internal(), -2.5);
 };
 
 TEST_F(LAMMPS_extract_variable, equal)
diff --git a/unittest/python/python-commands.py b/unittest/python/python-commands.py
index 1c25751191..c9f16f6a71 100644
--- a/unittest/python/python-commands.py
+++ b/unittest/python/python-commands.py
@@ -475,6 +475,26 @@ create_atoms 1 single &
         a = self.lmp.extract_variable("a")
         self.assertEqual(a, 3.14)
 
+    def test_extract_variable_stringstyle(self):
+        self.lmp.command("variable a string xxx")
+        a = self.lmp.extract_variable("a")
+        self.assertEqual(a, 'xxx')
+
+        rv = self.lmp.set_string_variable("a","20")
+        a = self.lmp.extract_variable("a")
+        self.assertEqual(a, '20')
+        self.assertEqual(rv, 0)
+
+    def test_extract_variable_internalstyle(self):
+        self.lmp.command("variable a internal 2.0")
+        a = self.lmp.extract_variable("a")
+        self.assertEqual(a, 2.0)
+
+        rv = self.lmp.set_internal_variable("a",-4.5)
+        a = self.lmp.extract_variable("a")
+        self.assertEqual(a, -4.5)
+        self.assertEqual(rv, 0)
+
     def test_extract_variable_atomstyle(self):
         self.lmp.command("units lj")
         self.lmp.command("atom_style atomic")