diff --git a/src/halmos/config.py b/src/halmos/config.py
index 5efd21fa..7eb56088 100644
--- a/src/halmos/config.py
+++ b/src/halmos/config.py
@@ -13,11 +13,12 @@
 internal = "internal"
 
 # groups
-debugging, solver, build, experimental = (
+debugging, solver, build, experimental, deprecated = (
     "Debugging options",
     "Solver options",
     "Build options",
     "Experimental options",
+    "Deprecated options",
 )
 
 
@@ -343,10 +344,6 @@ class Config:
         group=solver,
     )
 
-    solver_parallel: bool = arg(
-        help="run assertion solvers in parallel", global_default=False, group=solver
-    )
-
     solver_threads: int = arg(
         help="set the number of threads for parallel solvers",
         metavar="N",
@@ -381,6 +378,14 @@ class Config:
         group=experimental,
     )
 
+    ### Deprecated
+
+    solver_parallel: bool = arg(
+        help="(Deprecated; no-op; use --solver-threads instead) run assertion solvers in parallel",
+        global_default=False,
+        group=deprecated,
+    )
+
     ### Methods
 
     def __getattribute__(self, name):