diff --git a/.github/generate-job-matrix.py b/.github/generate-job-matrix.py
index ae06b9ce..d711d3cc 100644
--- a/.github/generate-job-matrix.py
+++ b/.github/generate-job-matrix.py
@@ -4,7 +4,7 @@ import random
 import typing
 from types import SimpleNamespace
 
-from job_matrix import CombinationCollector, Compiler, Configuration, dataclass_to_json
+from job_matrix import CombinationCollector, Compiler, Configuration
 
 
 def make_gcc_config(version: int) -> Configuration:
@@ -155,20 +155,20 @@ def main():
 
     data = sorted(collector.combinations)
 
+    json_data = [e.as_json() for e in data]
+
     if not args.suppress_output:
-        print(
-            f"::set-output name=matrix::{json.dumps(data, default=dataclass_to_json)}"
-        )
+        print(f"::set-output name=matrix::{json.dumps(json_data)}")
 
     for dbg in args.debug:
         match dbg:
             case "yaml":
                 import yaml
 
-                json_data = json.loads(json.dumps(data, default=dataclass_to_json))
+                json_data = json.loads(json.dumps(json_data))
                 print(yaml.safe_dump(json_data))
             case "json":
-                print(json.dumps(data, default=dataclass_to_json, indent=4))
+                print(json.dumps(json_data, indent=4))
             case "combinations":
                 for e in data:
                     print(
diff --git a/.github/job_matrix.py b/.github/job_matrix.py
index eb956268..204be679 100644
--- a/.github/job_matrix.py
+++ b/.github/job_matrix.py
@@ -35,12 +35,21 @@ class MatrixElement:
     contracts: typing.Literal["none", "gsl-lite", "ms-gsl"]
     build_type: typing.Literal["Release", "Debug"]
 
+    def as_json(self):
+        def dataclass_to_json(obj):
+            """Convert dataclasses to something json-serialisable"""
+            if dataclasses.is_dataclass(obj):
+                return {
+                    k: dataclass_to_json(v) for k, v in dataclasses.asdict(obj).items()
+                }
+            return obj
 
-def dataclass_to_json(obj):
-    """Convert dataclasses to something json-serialisable"""
-    if dataclasses.is_dataclass(obj):
-        return dataclasses.asdict(obj)
-    raise TypeError(f"Unknown object of type {type(obj).__name__}")
+        ret = dataclass_to_json(self)
+        # patch boolean conan configuration options
+        config = ret["config"]
+        for k in ["cxx_modules"]:
+            config[k] = "True" if config[k] else "False"
+        return ret
 
 
 class CombinationCollector: