diff --git a/.github/workflows/regression.yml b/.github/workflows/regression.yml
index ff68a7a024b..992a0d6e30a 100644
--- a/.github/workflows/regression.yml
+++ b/.github/workflows/regression.yml
@@ -122,6 +122,8 @@ jobs:
         with:
           entrypoint: /bin/rm
           args: -rf install install_bin.tgz src ccache ${{ matrix.config_set }}
+      - name: Lower ASLR entropy for TSan
+        run: sudo sysctl vm.mmap_rnd_bits=28
       - name: Build
         uses: docker://ghcr.io/su2code/su2/build-su2-tsan:261011-1107
         with:
@@ -324,6 +326,8 @@ jobs:
           done
           chmod a+x $BIN_FOLDER/*
           ls -lahR $BIN_FOLDER
+      - name: Lower ASLR entropy for TSan
+        run: sudo sysctl vm.mmap_rnd_bits=28
       - name: Run Tests in Container
         uses: docker://ghcr.io/su2code/su2/test-su2-tsan:261011-1107
         env:
diff --git a/preconfigure.py b/preconfigure.py
index bfba6995c5b..f379baa9f86 100755
--- a/preconfigure.py
+++ b/preconfigure.py
@@ -73,6 +73,13 @@ def build_ninja():
             # Specify C++17
             env = os.environ.copy()
             env["CXXFLAGS"] = env.get("CXXFLAGS", "") + " -std=c++17"
+            # ninja is a build tool and must not be instrumented by sanitizers
+            for var in ("CFLAGS", "CXXFLAGS", "LDFLAGS"):
+                env[var] = " ".join(
+                    f
+                    for f in env.get(var, "").split()
+                    if not f.startswith("-fsanitize")
+                )
             subprocess.run(
                 ["python3", "configure.py", "--bootstrap"], cwd=ninjapath, env=env
             )