diff --git a/snakemake/resources.py b/snakemake/resources.py
index a343cf458..3dd052e64 100644
--- a/snakemake/resources.py
+++ b/snakemake/resources.py
@@ -20,7 +20,7 @@ class DefaultResources:
     @classmethod
     def decode_arg(cls, arg):
         try:
-            return arg.split("=")
+            return arg.split("=", maxsplit=1)
         except ValueError:
             raise ValueError("Resources have to be defined as name=value pairs.")
 
diff --git a/tests/test_slurm.py b/tests/test_slurm.py
index 88e6822e0..0f49348e1 100644
--- a/tests/test_slurm.py
+++ b/tests/test_slurm.py
@@ -80,3 +80,20 @@ def test_slurm_complex():
             ]
         ),
     )
+
+
+@skip_on_windows
+def test_slurm_extra_arguments():
+    """Make sure arguments to default resources
+    are allowed to contain = signs, which is needed
+    for extra slurm arguments"""
+    run(
+        dpath("test_slurm_mpi"),
+        slurm=True,
+        show_failed_logs=True,
+        use_conda=True,
+        default_resources=DefaultResources(
+            ["slurm_account=runner", "slurm_partition=debug",
+             "slurm_extra='--mail-type=none'"]
+        ),
+    )