diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 0c725ee..fdbe192 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -60,16 +60,16 @@ jobs:
       - name: Ensure lockfile exists
         run: |
           if [ ! -f uv.lock ]; then
-            uv lock
+            uv lock --python "${{ matrix.python-version }}"
           else
             uv lock --check
           fi
 
       - name: Run tests on Python ${{ matrix.python-version }}
         run: |
-          uv venv
+          uv venv --python "${{ matrix.python-version }}"
           source .venv/bin/activate
-          uv sync --locked --all-extras --dev
+          uv sync --python "${{ matrix.python-version }}" --locked --all-extras --dev
 
           # Run standalone examples through their public default target.
           for ex in basic adder TinyALU_SystemC; do
diff --git a/.python-version b/.python-version
index e4fba21..6324d40 100644
--- a/.python-version
+++ b/.python-version
@@ -1 +1 @@
-3.12
+3.14
diff --git a/README.md b/README.md
index 27c5d3b..c33075d 100644
--- a/README.md
+++ b/README.md
@@ -70,7 +70,7 @@ Additional signal types can be added as needed.
 
 - SystemC 3.0.2
 - CMake 3.15 or newer
-- Python 3.11 or newer
+- Python 3.12 or newer
 - uv
 
 Install the Python dependencies (including **cocotb 2.x** and
@@ -156,4 +156,4 @@ make -C examples/tinyalu_reg run-sc-tlm-target-wait RANDOM_SEED=12345
 ## License
 
 This project is released under the applicable open-source license.
-Third-party examples and testbenches retain their original licenses.
\ No newline at end of file
+Third-party examples and testbenches retain their original licenses.
diff --git a/examples/TinyALU_SystemC/Makefile b/examples/TinyALU_SystemC/Makefile
index ba05098..a0a8652 100644
--- a/examples/TinyALU_SystemC/Makefile
+++ b/examples/TinyALU_SystemC/Makefile
@@ -19,7 +19,8 @@ COCOTB_LIBPYTHON     = $(shell $(COCOTB_CMD) --libpython 2>/dev/null || echo "")
 COCOTB_LIBPYTHON_DIR = $(dir $(COCOTB_LIBPYTHON))
 COCOTB_PYTHON_BIN    = $(shell $(COCOTB_CMD) --python-bin 2>/dev/null || echo "python3")
 COCOTB_LIB_DIR       = $(shell $(COCOTB_CMD) --lib-dir 2>/dev/null || echo "")
-COCOTB_VPI_ICARUS    = $(COCOTB_LIB_DIR)/libcocotbvpi_icarus.vpl
+COCOTB_PYGPI_ENTRY   = $(shell $(COCOTB_CMD) --pygpi-entry-point 2>/dev/null || echo "")
+COCOTB_VPI_ICARUS    = $(shell $(COCOTB_CMD) --lib-name-path vpi icarus 2>/dev/null || echo "")
 
 RESULTS_FILE    := $(CURDIR)/results.xml
 RESULTS_CHECKER := $(CURDIR)/../../tools/check_cocotb_results.py
@@ -27,6 +28,7 @@ RESULTS_CHECKER := $(CURDIR)/../../tools/check_cocotb_results.py
 COCOTB_ENV = \
 	PYTHONPATH=.:$$PYTHONPATH \
 	PYGPI_PYTHON_BIN=$(COCOTB_PYTHON_BIN) \
+	GPI_USERS="$(COCOTB_LIBPYTHON);$(COCOTB_PYGPI_ENTRY)" \
 	COCOTB_TEST_MODULES=testbench \
 	COCOTB_RESULTS_FILE=$(RESULTS_FILE) \
 	COCOTB_RANDOM_SEED=$(RANDOM_SEED) \
diff --git a/examples/adder/Makefile b/examples/adder/Makefile
index ad371a6..b4b0198 100644
--- a/examples/adder/Makefile
+++ b/examples/adder/Makefile
@@ -23,7 +23,8 @@ COCOTB_LIBPYTHON     = $(shell $(COCOTB_CMD) --libpython 2>/dev/null || echo "")
 COCOTB_LIBPYTHON_DIR = $(dir $(COCOTB_LIBPYTHON))
 COCOTB_PYTHON_BIN    = $(shell $(COCOTB_CMD) --python-bin 2>/dev/null || echo "python3")
 COCOTB_LIB_DIR       = $(shell $(COCOTB_CMD) --lib-dir 2>/dev/null || echo "")
-COCOTB_VPI_ICARUS    = $(COCOTB_LIB_DIR)/libcocotbvpi_icarus.vpl
+COCOTB_PYGPI_ENTRY   = $(shell $(COCOTB_CMD) --pygpi-entry-point 2>/dev/null || echo "")
+COCOTB_VPI_ICARUS    = $(shell $(COCOTB_CMD) --lib-name-path vpi icarus 2>/dev/null || echo "")
 
 RESULTS_FILE    := $(CURDIR)/results.xml
 RESULTS_CHECKER := $(CURDIR)/../../tools/check_cocotb_results.py
@@ -31,6 +32,7 @@ RESULTS_CHECKER := $(CURDIR)/../../tools/check_cocotb_results.py
 COCOTB_ENV = \
 	PYTHONPATH=.:$$PYTHONPATH \
 	PYGPI_PYTHON_BIN=$(COCOTB_PYTHON_BIN) \
+	GPI_USERS="$(COCOTB_LIBPYTHON);$(COCOTB_PYGPI_ENTRY)" \
 	COCOTB_TEST_MODULES=tb \
 	COCOTB_RESULTS_FILE=$(RESULTS_FILE) \
 	COCOTB_RANDOM_SEED=$(RANDOM_SEED) \
diff --git a/examples/basic/Makefile b/examples/basic/Makefile
index adbebdc..367f210 100644
--- a/examples/basic/Makefile
+++ b/examples/basic/Makefile
@@ -33,12 +33,13 @@ COCOTB_LIBPYTHON     = $(shell $(COCOTB_CMD) --libpython 2>/dev/null || echo "")
 COCOTB_LIBPYTHON_DIR = $(dir $(COCOTB_LIBPYTHON))
 COCOTB_PYTHON_BIN    = $(shell $(COCOTB_CMD) --python-bin 2>/dev/null || echo "python3")
 COCOTB_LIB_DIR       = $(shell $(COCOTB_CMD) --lib-dir 2>/dev/null || echo "")
+COCOTB_PYGPI_ENTRY   = $(shell $(COCOTB_CMD) --pygpi-entry-point 2>/dev/null || echo "")
 
 # VPI library paths
-COCOTB_VPI_VERILATOR = $(COCOTB_LIB_DIR)/libcocotbvpi_verilator.so
-COCOTB_VPI_QUESTA    = $(COCOTB_LIB_DIR)/libcocotbvpi_modelsim.so
-COCOTB_VPI_XCELIUM   = $(COCOTB_LIB_DIR)/libcocotbvpi_ius.so
-COCOTB_VPI_ICARUS    = $(COCOTB_LIB_DIR)/libcocotbvpi_icarus.vpl
+COCOTB_VPI_VERILATOR = $(shell $(COCOTB_CMD) --lib-name-path vpi verilator 2>/dev/null || echo "")
+COCOTB_VPI_QUESTA    = $(shell $(COCOTB_CMD) --lib-name-path vpi questa 2>/dev/null || echo "")
+COCOTB_VPI_XCELIUM   = $(shell $(COCOTB_CMD) --lib-name-path vpi xcelium 2>/dev/null || echo "")
+COCOTB_VPI_ICARUS    = $(shell $(COCOTB_CMD) --lib-name-path vpi icarus 2>/dev/null || echo "")
 
 # ------------------------------------------------------------------------------
 # Build Configurations
@@ -58,6 +59,7 @@ ICARUS_LDFLAGS    = $(SYSTEMC_LDFLAGS) $(BASE_LDFLAGS)
 BASE_COCOTB_ENV = \
 	PYTHONPATH=.:$$PYTHONPATH \
 	PYGPI_PYTHON_BIN=$(COCOTB_PYTHON_BIN) \
+	GPI_USERS="$(COCOTB_LIBPYTHON);$(COCOTB_PYGPI_ENTRY)" \
 	COCOTB_TEST_MODULES=tb \
 	COCOTB_RESULTS_FILE=$(RESULTS_FILE) \
 	COCOTB_RANDOM_SEED=$(RANDOM_SEED)
diff --git a/examples/tinyalu_reg/Makefile b/examples/tinyalu_reg/Makefile
index 4499a57..abd45d2 100644
--- a/examples/tinyalu_reg/Makefile
+++ b/examples/tinyalu_reg/Makefile
@@ -35,10 +35,11 @@ SIM_EXE := $(BUILD_DIR)/TINYALU_REG_SC
 
 COCOTB_CMD := $(PYTHON) -m cocotb_tools.config
 COCOTB_LIB_DIR := $(shell $(COCOTB_CMD) --lib-dir 2>/dev/null)
-VPI_SO := $(COCOTB_LIB_DIR)/libcocotbvpi_icarus.vpl
+VPI_SO := $(shell $(COCOTB_CMD) --lib-name-path vpi icarus 2>/dev/null)
 
 COCOTB_LIBPYTHON := $(shell $(COCOTB_CMD) --libpython 2>/dev/null)
 COCOTB_LIBPYTHON_DIR := $(dir $(COCOTB_LIBPYTHON))
+COCOTB_PYGPI_ENTRY := $(shell $(COCOTB_CMD) --pygpi-entry-point 2>/dev/null)
 
 RESULTS_FILE := $(CURDIR)/results_$(MODEL).xml
 RESULTS_CHECKER := $(CURDIR)/../../tools/check_cocotb_results.py
@@ -117,6 +118,7 @@ else
 		PATH="$$(dirname "$(PYTHON)"):$$PATH" \
 		PYTHONHOME= \
 		PYGPI_PYTHON_BIN="$(PYTHON)" \
+		GPI_USERS="$(COCOTB_LIBPYTHON);$(COCOTB_PYGPI_ENTRY)" \
 		COCOTB_TEST_MODULES=tests.testbench \
 		COCOTB_RESULTS_FILE="$(RESULTS_FILE)" \
 		COCOTB_RANDOM_SEED="$(RANDOM_SEED)" \
@@ -210,4 +212,4 @@ help:
 .PHONY: clean
 clean:
 	rm -rf build_hdl build_rtl build_tlm traces results*.xml sim_build __pycache__ tests/__pycache__
-	$(MAKE) -C model_hdl clean PYTHON="$(PYTHON)" || true
\ No newline at end of file
+	$(MAKE) -C model_hdl clean PYTHON="$(PYTHON)" SIM=icarus || true
\ No newline at end of file
diff --git a/src/vpi.icc b/src/vpi.icc
index 386ce22..3d7d3ac 100644
--- a/src/vpi.icc
+++ b/src/vpi.icc
@@ -636,6 +636,7 @@ PLI_INT32 vpi_get(PLI_INT32 property, vpiHandle object) {
     }
 
     auto itH = g_handles.find(object);
+
     if (property == vpiType) {
         return (itH != g_handles.end()) ? itH->second->vpi_type : 0;
     }
@@ -648,7 +649,33 @@ PLI_INT32 vpi_get(PLI_INT32 property, vpiHandle object) {
         return 1;
     }
 
+    // cocotb 2.1 queries VPI signedness for integer objects.
+    if (property == vpiSigned) {
+        if (itH == g_handles.end()) {
+            return 0;
+        }
+
+        switch (itH->second->kind) {
+        case SigInt32:
+        case SigInt4:
+            return 1;
+
+        case SigBool:
+        case SigUInt3:
+        case SigUInt4:
+        case SigUInt5:
+        case SigUInt8:
+        case SigUInt9:
+        case SigUInt16:
+        case SigUInt32:
+        case SigUnknown:
+        default:
+            return 0;
+        }
+    }
+
     if (property == vpiTimePrecision || property == vpiTimeUnit) return -9;
+
     return 0;
 }