diff --git a/.github/actions/with-docker/Dockerfile b/.github/actions/with-docker/Dockerfile
index feb92b2..330e2ec 100644
--- a/.github/actions/with-docker/Dockerfile
+++ b/.github/actions/with-docker/Dockerfile
@@ -32,4 +32,4 @@ RUN    curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | bash -s -- -y
     && rustup target add wasm32-unknown-unknown \
     && rustup target add wasm32v1-none
 
-RUN cargo install --locked stellar-cli
+RUN cargo install --locked stellar-cli@23.1.4
diff --git a/flake.nix b/flake.nix
index 65e203e..0e6df6a 100644
--- a/flake.nix
+++ b/flake.nix
@@ -69,6 +69,16 @@
             (finalPython: prevPython: {
               kframework = k-framework.packages.${system}.pyk-python310;
               pykwasm = wasm-semantics.packages.${system}.kwasm-pyk;
+              # override numpy on Darwin to avoid the missing dynamic library issue
+              numpy = if pkgs.stdenv.isDarwin
+                then
+                  prevPython.numpy.overrideAttrs (old: {
+                    buildInputs = (old.buildInputs or []) ++ [ pkgs.Accelerate ];
+                    NPY_BLAS_ORDER = "accelerate";
+                    NPY_LAPACK_ORDER = "accelerate";
+                  })
+                else
+                  prevPython.numpy;
             });
           groups = [ ];
           checkGroups = [ ];
diff --git a/package/version b/package/version
index 8076b7d..416eb55 100644
--- a/package/version
+++ b/package/version
@@ -1 +1 @@
-0.1.72
+0.1.73
diff --git a/pyproject.toml b/pyproject.toml
index a16b48d..d11ad4f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "poetry.core.masonry.api"
 
 [tool.poetry]
 name = "komet"
-version = "0.1.72"
+version = "0.1.73"
 description = "K tooling for the Soroban platform"
 authors = [
     "Runtime Verification, Inc. <contact@runtimeverification.com>",
diff --git a/src/komet/kasmer.py b/src/komet/kasmer.py
index 6820974..acfcad2 100644
--- a/src/komet/kasmer.py
+++ b/src/komet/kasmer.py
@@ -42,7 +42,7 @@
 )
 from .proof import is_functional, run_claim, run_functional_claim
 from .scval import SCType
-from .utils import KSorobanError, concrete_definition
+from .utils import KSorobanError, concrete_definition, subst_on_program_cell
 
 if TYPE_CHECKING:
     from collections.abc import Iterable, Mapping
@@ -248,6 +248,7 @@ def scval_to_kore(val: SCValue) -> Pattern:
             check_exit_code=True,
             max_examples=max_examples,
             handler=KometFuzzHandler(self.definition, task),
+            subst_func=subst_on_program_cell,
         )
 
     def run_prove(
diff --git a/src/komet/utils.py b/src/komet/utils.py
index 15e0e56..dced9cb 100644
--- a/src/komet/utils.py
+++ b/src/komet/utils.py
@@ -8,18 +8,23 @@
 from pyk.kast.outer import KRule, read_kast_definition
 from pyk.kdist import kdist
 from pyk.konvert import kast_to_kore
+from pyk.kore.manip import substitute_vars
+from pyk.kore.prelude import generated_top
+from pyk.kore.syntax import App
 from pyk.ktool.kompile import DefinitionInfo
 from pyk.ktool.kprove import KProve
 from pyk.ktool.krun import KRun
 from pyk.utils import single
 
 if TYPE_CHECKING:
+    from collections.abc import Mapping
     from pathlib import Path
     from subprocess import CompletedProcess
     from typing import Any, Final
 
     from pyk.kast.inner import KInner, KSort
     from pyk.kast.outer import KDefinition, KFlatModule
+    from pyk.kore.syntax import EVar, Pattern
     from pyk.ktool.kompile import KompileBackend
 
 _LOGGER: Final = logging.getLogger(__name__)
@@ -92,3 +97,29 @@ def parse_lemmas_module(self, module_path: Path, module_name: str) -> KFlatModul
 concrete_definition = SorobanDefinition(kdist.get('soroban-semantics.llvm'))
 library_definition = SorobanDefinition(kdist.get('soroban-semantics.llvm-library'))
 symbolic_definition = SorobanDefinition(kdist.get('soroban-semantics.haskell'))
+
+
+def subst_on_program_cell(template: Pattern, subst_case: Mapping[EVar, Pattern]) -> Pattern:
+    """A substitution function that only applies substitutions within the K cell.
+    Optimizing the fuzzer by restricting changes to relevant parts of the configuration.
+
+    Args:
+        template: The template configuration containing variables in the K cell.
+        subst_case: A mapping from variables to their replacement patterns.
+    """
+
+    def kasmer_cell(program_cell: Pattern, soroban_cell: Pattern, exit_code_cell: Pattern) -> Pattern:
+        return App("Lbl'-LT-'kasmer'-GT-'", args=(program_cell, soroban_cell, exit_code_cell))
+
+    match template:
+        case App(
+            "Lbl'-LT-'generatedTop'-GT-'",
+            args=(
+                App("Lbl'-LT-'kasmer'-GT-'", args=(program_cell, soroban_cell, exit_code_cell)),
+                generated_counter_cell,
+            ),
+        ):
+            program_cell_ = substitute_vars(program_cell, subst_case)
+            return generated_top((kasmer_cell(program_cell_, soroban_cell, exit_code_cell), generated_counter_cell))
+
+    raise ValueError(template)