diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 3b3bc458c7..16b68ca12b 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -31,6 +31,7 @@ Since last release
 **Removed:**
 
 * Removed the ResourceBuff class and replaced its instances with ResBuf (#1755)
+* Removed reference to deprecated ``ProgTranslator::Context`` class (#1811)
 
 **Fixed:**
 
@@ -38,6 +39,7 @@ Since last release
 * Removed GTest source code from code coverage reports (#1759)
 * Updated action versions to avoid node.js deprecation (#1802)
 * Removed the module imports in `cyclus/__init__.py` and removed the need for multi-phase initialization of Cython modules (#1809)
+* No longer use deprecated Numpy Cython api when Cython>=3 (#1811)
 * ResTracker Extract gave the wrong parent_id to one of the child resources (#1806)
 
 
diff --git a/cyclus/CMakeLists.txt b/cyclus/CMakeLists.txt
index 6c9179b02c..463c4ec0bb 100644
--- a/cyclus/CMakeLists.txt
+++ b/cyclus/CMakeLists.txt
@@ -38,6 +38,9 @@ foreach(file ${CYCLUS_CYTHON_FILES})
     set_target_properties(${targ} PROPERTIES LINKER_LANGUAGE CXX
                                              OUTPUT_NAME ${name}
                                              LIBRARY_OUTPUT_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}")
+    if (CYTHON_VERSION_MAJOR GREATER_EQUAL 3)
+        target_compile_definitions(${targ} PRIVATE NPY_NO_DEPRECATED_API=NPY_1_7_API_VERSION)
+    endif()
     # the following install is needed so that CMake sets the correct RPATH for the
     # python extension modules, even though they are installed (with the wrong RPATH)
     # by setup.py, along with the pure python files.
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 3f948191a3..d05b552d7d 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -150,12 +150,15 @@ if(Cython_FOUND)
 
         ADD_LIBRARY(${name} ${_cc_file})
         SET(CythonModuleSrc ${CythonModuleSrc} ${_cc_file})
-        SET_TARGET_PROPERTIES(${name} PROPERTIES 
+        SET_TARGET_PROPERTIES(${name} PROPERTIES
           OUTPUT_NAME "${name}"
           PREFIX ""
           INSTALL_NAME_DIR "${CMAKE_INSTALL_PREFIX}/lib"
           INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/lib"
           )
+        IF (CYTHON_VERSION_MAJOR GREATER_EQUAL 3)
+            TARGET_COMPILE_DEFINITIONS(${name} PRIVATE NPY_NO_DEPRECATED_API=NPY_1_7_API_VERSION)
+        ENDIF()
 
         TARGET_LINK_LIBRARIES(${name} dl ${NoCythonLibs})
 
diff --git a/src/context.h b/src/context.h
index 3892006f58..e46a11e09c 100644
--- a/src/context.h
+++ b/src/context.h
@@ -198,8 +198,14 @@ class Context {
     }
 
     Agent* m = protos_[proto_name];
+    if (m == NULL) {
+        throw KeyError("Null prototype for " + proto_name);
+    }
     T* casted(NULL);
     Agent* clone = m->Clone();
+    if (clone == NULL) {
+        throw StateError("Clone operation failed for " + proto_name);
+    }
     casted = dynamic_cast<T*>(clone);
     if (casted == NULL) {
       PyDelAgent(clone->id());
diff --git a/src/infile_tree.cc b/src/infile_tree.cc
index 1540b4c7ff..5af4fa575d 100644
--- a/src/infile_tree.cc
+++ b/src/infile_tree.cc
@@ -10,7 +10,7 @@
 
 namespace cyclus {
 
-#if LIBXMLXX_MAJOR_VERSION == 2 
+#if LIBXMLXX_MAJOR_VERSION == 2
   typedef xmlpp::NodeSet NodeSet;
   typedef xmlpp::Node::NodeList const_NodeList;
 #else
@@ -76,7 +76,7 @@ std::string InfileTree::GetString(std::string query, int index) {
     dynamic_cast<const Element*>(nodeset.at(index));
 
   if (!element) {
-    throw CastError("Node: " + element->get_name() +
+    throw CastError("Node: " + nodeset.at(index)->get_name() +
                     " is not an Element node.");
   }
 
@@ -90,7 +90,7 @@ std::string InfileTree::GetString(std::string query, int index) {
     dynamic_cast<const xmlpp::TextNode*>(element->get_children().front());
 
   if (!text) {
-    throw CastError("Node: " + text->get_name() + " is not a Text node.");
+    throw CastError("Node: " + element->get_name() + " is not a Text node.");
   }
 
   return text->get_content();
@@ -129,7 +129,7 @@ InfileTree* InfileTree::GetEngineFromQuery(std::string query, int index) {
   xmlpp::Element* element = dynamic_cast<xmlpp::Element*>(nodeset.at(index));
 
   if (!element) {
-    throw CastError("Node: " + element->get_name() +
+    throw CastError("Node: " + nodeset.at(index)->get_name() +
                     " is not an Element node.");
   }
 
diff --git a/src/package.cc b/src/package.cc
index b5ab64e301..1e601c5b20 100644
--- a/src/package.cc
+++ b/src/package.cc
@@ -146,6 +146,7 @@ int TransportUnit::MaxShippablePackages(int pkgs) {
     }
     return shippable;
   }
+  return 0;
 }
   
 TransportUnit::TransportUnit(std::string name, int fill_min, int fill_max, std::string strategy) : 
diff --git a/src/prog_translator.cc b/src/prog_translator.cc
index cf6a284442..50d387c541 100644
--- a/src/prog_translator.cc
+++ b/src/prog_translator.cc
@@ -230,15 +230,5 @@ void ProgTranslator::FromProg() {
   }
 }
 
-ProgTranslator::Context::Context() {
-  throw DepricationError("Class ProgTranslator::Context is now deprecated "
-                         "in favor of ProgTranslatorContext.");
-}
-
-ProgTranslator::Context::~Context() {
-  throw DepricationError("Class ProgTranslator::Context is now deprecated "
-                         "in favor of ProgTranslatorContext.");
-}
-
 
 }  // namespace cyclus
diff --git a/src/toolkit/building_manager.cc b/src/toolkit/building_manager.cc
index adfe55f1d9..ea616438e9 100644
--- a/src/toolkit/building_manager.cc
+++ b/src/toolkit/building_manager.cc
@@ -3,8 +3,6 @@
 #include "prog_translator.h"
 #include "CoinPackedVector.hpp"
 
-// Headers in this file below this pragma have all warnings shushed.
-#pragma GCC system_header
 #include "OsiCbcSolverInterface.hpp"
 
 namespace cyclus {
diff --git a/src/toolkit/matl_sell_policy.cc b/src/toolkit/matl_sell_policy.cc
index 50e6105e18..f6f86980ea 100644
--- a/src/toolkit/matl_sell_policy.cc
+++ b/src/toolkit/matl_sell_policy.cc
@@ -208,13 +208,13 @@ std::set<BidPortfolio<Material>::Ptr> MatlSellPolicy::GetMatlBids(
         // overflow to negative int limit 
         std::string s;
         if (manager() != NULL)
-          s + " Agent: "
+          s += " Agent: "
             + Trader::manager()->prototype() + "-"
             + std::to_string(Trader::manager()->id()) + ". ";
-        s + "This is likely due to too much material (did you forget a "
-          + "throughput?) or small package limits relative to the "
-          + "quantity available. qty: " + std::to_string(qty) 
-          + ", and each bid would be: " + std::to_string(bid_qty);
+        s += "This is likely due to too much material (did you forget a ";
+        s += "throughput?) or small package limits relative to the ";
+        s += "quantity available. qty: " + std::to_string(qty);
+        s += ", and each bid would be: " + std::to_string(bid_qty);
         Package::ExceedsSplitLimits(n_full_bids, s);
 
         bids.assign(n_full_bids, bid_qty);
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index eb6138bf28..2acf0a7d3a 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -7,7 +7,10 @@ SET(GENERATED_TEST_LIST "" CACHE INTERNAL "")
 SET(GENERATED_FILTER_LIST "" CACHE INTERNAL "")
 SET(GENERATED_TEST_SOURCE_LIST "" CACHE INTERNAL "")
 
-include(FetchContent)
+INCLUDE(FetchContent)
+IF (CMAKE_VERSION GREATER_EQUAL 3.24)
+    CMAKE_POLICY(SET CMP0135 NEW)
+ENDIF()
 FetchContent_Declare(
   googletest
   BUILD_GMOCK FALSE # do not build googlemock subproject
diff --git a/tests/prog_translator_tests.cc b/tests/prog_translator_tests.cc
index 63ab0b17b8..c7c20dfc16 100644
--- a/tests/prog_translator_tests.cc
+++ b/tests/prog_translator_tests.cc
@@ -280,11 +280,5 @@ TEST(ProgTranslatorTests, translation) {
   delete iface;
 }
 
-TEST(ProgTranslatorTests, depricated) {
-
-  // confirm depricated error is thrown
-  ASSERT_THROW(new ProgTranslator::Context(), DepricationError);
-}
-
 
 }  // namespace cyclus