diff --git a/buildingspy/CHANGES.txt b/buildingspy/CHANGES.txt
index 5ae70327..6797b918 100644
--- a/buildingspy/CHANGES.txt
+++ b/buildingspy/CHANGES.txt
@@ -1,6 +1,14 @@
 BuildingsPy Changelog
 ---------------------
 
+
+Version 5.2.1, ...
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+- In buildingspy/development/regressiontest.py, added test for OpenModelica and
+  OPTIMICA CI testing that issues an error if a pure function calls an impure function.
+  (https://github.com/lbl-srg/BuildingsPy/issues/607)
+
 Version 5.2.0, March 14, 2025
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
diff --git a/buildingspy/VERSION b/buildingspy/VERSION
index 91ff5727..26d99a28 100644
--- a/buildingspy/VERSION
+++ b/buildingspy/VERSION
@@ -1 +1 @@
-5.2.0
+5.2.1
diff --git a/buildingspy/development/error_dictionary_openmodelica.py b/buildingspy/development/error_dictionary_openmodelica.py
index 8f74f5ab..d82f0a00 100644
--- a/buildingspy/development/error_dictionary_openmodelica.py
+++ b/buildingspy/development/error_dictionary_openmodelica.py
@@ -39,3 +39,8 @@ def __init__(self):
             'tool_message': "Non-array modification",
             'counter': 0,
             'summary_message': "Number of models with missing 'each'                         : {}\n"}
+
+        self._error_dict["pure calling impure function"] = {
+            'tool_message': "call to impure function",
+            'counter': 0,
+            'summary_message': "Number of models in which pure function calls impure function: {}\n"}
\ No newline at end of file
diff --git a/buildingspy/development/error_dictionary_optimica.py b/buildingspy/development/error_dictionary_optimica.py
index ac81a5d7..48f5ab8e 100644
--- a/buildingspy/development/error_dictionary_optimica.py
+++ b/buildingspy/development/error_dictionary_optimica.py
@@ -78,3 +78,9 @@ def __init__(self):
             'tool_message': "Integer, using Real instead",
             'counter': 0,
             'summary_message': "Number of models with too large Integers                        : {}\n"}
+
+        # Check for pure function calling impure function
+        self._error_dict["pure calling impure function"] = {
+            'tool_message': "Call to impure function",
+            'counter': 0,
+            'summary_message': "Number of models in which pure function calls impure function: {}\n"}
\ No newline at end of file
diff --git a/buildingspy/tests/test_development_regressiontest_openmodelica.py b/buildingspy/tests/test_development_regressiontest_openmodelica.py
index 7a96e71c..34edfe6c 100644
--- a/buildingspy/tests/test_development_regressiontest_openmodelica.py
+++ b/buildingspy/tests/test_development_regressiontest_openmodelica.py
@@ -319,7 +319,16 @@ def test_regressiontest_diagnostics(self):
              'mo_content': """Real x(start=0);
                                     equation
                                       Modelica.Math.exp(x)=-1;""",
-             'description': "Model that has no solution."}
+             'description': "Model that has no solution."},
+            {'ret_val': 1,
+             'mo_content': """
+  function aPureFunction
+  algorithm
+    Modelica.Utilities.Streams.print("Hello");
+  end aPureFunction;
+equation
+  aPureFunction();""",
+             'description': "Model in which a pure function calls an impure function."}
         ]
         # Run all test cases
         for test in tests:
diff --git a/buildingspy/tests/test_development_regressiontest_optimica.py b/buildingspy/tests/test_development_regressiontest_optimica.py
index 5a596a3f..388ae057 100644
--- a/buildingspy/tests/test_development_regressiontest_optimica.py
+++ b/buildingspy/tests/test_development_regressiontest_optimica.py
@@ -143,7 +143,16 @@ def test_regressiontest_diagnostics(self):
              'mo_content': """Real x(start=0);
                                     equation
                                       Modelica.Math.exp(x)=-1;""",
-             'description': "Model that has no solution."}
+             'description': "Model that has no solution."},
+            {'ret_val': 1,
+             'mo_content': """
+  function aPureFunction
+  algorithm
+    Modelica.Utilities.Streams.print("Hello");
+  end aPureFunction;
+equation
+  aPureFunction();""",
+             'description': "Model in which a pure function calls an impure function."}
         ]
         # Run all test cases
         for test in tests: