diff --git a/snakemake_executor_plugin_slurm/partitions.py b/snakemake_executor_plugin_slurm/partitions.py
index f52cc4ed..89c025fc 100644
--- a/snakemake_executor_plugin_slurm/partitions.py
+++ b/snakemake_executor_plugin_slurm/partitions.py
@@ -3,6 +3,7 @@
 import yaml
 from pathlib import Path
 from math import inf, isinf
+from snakemake.common import tbdstring
 from snakemake_interface_common.exceptions import WorkflowError
 from snakemake_interface_executor_plugins.jobs import (
     JobExecutorInterface,
@@ -289,8 +290,11 @@ def score_job_fit(self, job: JobExecutorInterface) -> Optional[float]:
 
         for resource_key, limit in numerical_resources.items():
             job_requirement = job.resources.get(resource_key, 0)
+            # Skip TBD (not specified) resources entirely
+            if isinstance(job_requirement, tbdstring.TBDString):
+                job_requirement = 0
             # Convert to numeric value if it's a string
-            if isinstance(job_requirement, str):
+            elif isinstance(job_requirement, str):
                 try:
                     job_requirement = float(job_requirement)
                 except ValueError: