diff --git a/addons/FastJet/CMakeLists.txt b/addons/FastJet/CMakeLists.txt
index 6fb291a76c..e69b9d775d 100644
--- a/addons/FastJet/CMakeLists.txt
+++ b/addons/FastJet/CMakeLists.txt
@@ -12,6 +12,11 @@ fccanalyses_addon_build(FastJet
                                  ROOT::ROOTVecOps
                         INSTALL_COMPONENT fastjet)
 
+# Prefer FastJet's RPATH over LD_LIBRARY_PATH, so it doesn't pick up a
+# different FastJet build (e.g. Delphes' bundled copy) found earlier on
+# the search path.
+target_link_options(FastJet PRIVATE -Wl,--disable-new-dtags)
+
 add_custom_command(TARGET FastJet POST_BUILD
                    COMMAND ${CMAKE_COMMAND} -E copy
                    ${CMAKE_CURRENT_SOURCE_DIR}/python/*
diff --git a/analyzers/dataframe/FCCAnalyses/LinkSource.h b/analyzers/dataframe/FCCAnalyses/LinkSource.h
index 1237923f90..1c9ca3d7f1 100644
--- a/analyzers/dataframe/FCCAnalyses/LinkSource.h
+++ b/analyzers/dataframe/FCCAnalyses/LinkSource.h
@@ -59,7 +59,7 @@ struct selAbsPDG {
     }
 
     return result;
-  };
+  }
 };
 
 /**
diff --git a/python/run_analysis.py b/python/run_analysis.py
index eb162c2c12..f32ddd3aa4 100644
--- a/python/run_analysis.py
+++ b/python/run_analysis.py
@@ -432,7 +432,8 @@ def run_histmaker(args, rdf_module, anapath):
         LOGGER.error('Key4hep stack not setup!\nAborting...')
         sys.exit(3)
     k4h_stack_env = os.environ['KEY4HEP_STACK']
-    if 'sw-nightlies.hsf.org' in k4h_stack_env:
+    if ('sw-nightlies.hsf.org' in k4h_stack_env
+            or 'sft-nightlies.cern.ch' in k4h_stack_env):
         key4hep_stack = 'nightlies'
     elif 'sw.hsf.org' in k4h_stack_env:
         key4hep_stack = 'release'
@@ -440,12 +441,14 @@ def run_histmaker(args, rdf_module, anapath):
         LOGGER.error('Key4hep stack not recognized!\nAborting...')
         sys.exit(3)
 
-    if 'almalinux9' in k4h_stack_env:
+    if 'almalinux9' in k4h_stack_env or '-el9-' in k4h_stack_env:
         key4hep_os = 'alma9'
     elif 'ubuntu22' in k4h_stack_env:
         key4hep_os = 'ubuntu22'
     elif 'ubuntu24' in k4h_stack_env:
         key4hep_os = 'ubuntu24'
+    elif 'ubuntu26' in k4h_stack_env:
+        key4hep_os = 'ubuntu26'
     else:
         LOGGER.error('Key4hep OS not recognized!\nAborting...')
         sys.exit(3)
@@ -741,6 +744,10 @@ def run(parser):
             LOGGER.debug('Setting verbosity level "kDebug+10" for '
                          'RDataFrame...')
 
+    # Load real FastJet before Delphes gets pulled in via libFCCAnalyses,
+    # so ClusterSequence calls don't resolve into Delphes' bundled copy.
+    ROOT.gSystem.Load("libFastJet")
+
     # Load the pre-compiled analyzers
     LOGGER.info('Loading analyzers from libFCCAnalyses...')
     ROOT.gSystem.Load("libFCCAnalyses")
diff --git a/python/run_fccanalysis.py b/python/run_fccanalysis.py
index a0101a3619..262ee9a258 100644
--- a/python/run_fccanalysis.py
+++ b/python/run_fccanalysis.py
@@ -362,7 +362,8 @@ def merge_config(args: argparse.Namespace,
         LOGGER.error('Key4hep stack not setup!\nAborting...')
         sys.exit(3)
     k4h_stack_env = os.environ['KEY4HEP_STACK']
-    if 'sw-nightlies.hsf.org' in k4h_stack_env:
+    if ('sw-nightlies.hsf.org' in k4h_stack_env
+            or 'sft-nightlies.cern.ch' in k4h_stack_env):
         config['key4hep-stack'] = 'nightlies'
     elif 'sw.hsf.org' in k4h_stack_env:
         config['key4hep-stack'] = 'release'
@@ -370,7 +371,7 @@ def merge_config(args: argparse.Namespace,
         LOGGER.error('Key4hep stack not recognized!\nAborting...')
         sys.exit(3)
 
-    if 'almalinux9' in k4h_stack_env:
+    if 'almalinux9' in k4h_stack_env or '-el9-' in k4h_stack_env:
         config['key4hep-os'] = 'alma9'
     elif 'almalinux10' in k4h_stack_env:
         config['key4hep-os'] = 'alma10'
@@ -378,6 +379,8 @@ def merge_config(args: argparse.Namespace,
         config['key4hep-os'] = 'ubuntu22'
     elif 'ubuntu24' in k4h_stack_env:
         config['key4hep-os'] = 'ubuntu24'
+    elif 'ubuntu26' in k4h_stack_env:
+        config['key4hep-os'] = 'ubuntu26'
     else:
         LOGGER.error('Key4hep OS not recognized!\nAborting...')
         sys.exit(3)