diff --git a/Grammar/Grammar b/Grammar/Grammar
index 86ec43248e9..99fcea026a3 100644
--- a/Grammar/Grammar
+++ b/Grammar/Grammar
@@ -137,7 +137,7 @@ arglist: argument (',' argument)*  [',']
 argument: ( test [comp_for] |
             test '=' test |
             '**' test |
-            star_expr )
+            '*' test )
 
 comp_iter: comp_for | comp_if
 comp_for: 'for' exprlist 'in' or_test [comp_iter]
diff --git a/Lib/test/test_grammar.py b/Lib/test/test_grammar.py
index 8f0cf163eed..ec3d7833f7e 100644
--- a/Lib/test/test_grammar.py
+++ b/Lib/test/test_grammar.py
@@ -205,6 +205,8 @@ class GrammarTests(unittest.TestCase):
         d01()
         d01(1)
         d01(*(1,))
+        d01(*[] or [2])
+        d01(*() or (), *{} and (), **() or {})
         d01(**{'a':2})
         d01(**{'a':2} or {})
         def d11(a, b=1): pass
diff --git a/Misc/NEWS b/Misc/NEWS
index 11e19960d0a..56e61e299e8 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -40,6 +40,8 @@ Library
 - Issue #23812: Fix asyncio.Queue.get() to avoid loosing items on cancellation.
   Patch by Gustavo J. A. M. Carneiro.
 
+- Issue #24791: Fix grammar regression for call syntax: 'g(*a or b)'.
+
 Documentation
 -------------
 
diff --git a/Modules/parsermodule.c b/Modules/parsermodule.c
index 2a16dbacc62..8023558fd15 100644
--- a/Modules/parsermodule.c
+++ b/Modules/parsermodule.c
@@ -2859,8 +2859,8 @@ validate_arglist(node *tree)
 
 /*  argument: ( test [comp_for] |
  *              test '=' test |
- *              '**' expr |
- *              star_expr )
+ *              '**' test |
+ *              '*' test )
  */
 static int
 validate_argument(node *tree)
@@ -2873,8 +2873,11 @@ validate_argument(node *tree)
         if (TYPE(CHILD(tree, 0)) == DOUBLESTAR) {
             res = validate_test(CHILD(tree, 1));
         }
+        else if (TYPE(CHILD(tree, 0)) == STAR) {
+            res = validate_test(CHILD(tree, 1));
+        }
         else if (nch == 1) {
-            res = validate_test_or_star_expr(CHILD(tree, 0));
+            res = validate_test(CHILD(tree, 0));
         }
         else if (nch == 2) {
             res = (validate_test(CHILD(tree, 0))
diff --git a/Python/ast.c b/Python/ast.c
index bb28437ae2f..b572088a46c 100644
--- a/Python/ast.c
+++ b/Python/ast.c
@@ -2664,45 +2664,44 @@ ast_for_call(struct compiling *c, const node *n, expr_ty func)
             expr_ty e;
             node *chch = CHILD(ch, 0);
             if (NCH(ch) == 1) {
-                if (TYPE(chch) == star_expr) {
-                    /* an iterable argument unpacking */
-                    expr_ty starred;
+                /* a positional argument */
+                if (nkeywords) {
                     if (ndoublestars) {
                         ast_error(c, chch,
-                                "iterable argument unpacking follows "
+                                "positional argument follows "
                                 "keyword argument unpacking");
-                        return NULL;
                     }
-                    e = ast_for_expr(c, CHILD(chch, 1));
-                    if (!e)
-                        return NULL;
-                    starred = Starred(e, Load, LINENO(chch),
-                            chch->n_col_offset,
-                            c->c_arena);
-                    if (!starred)
-                        return NULL;
-                    asdl_seq_SET(args, nargs++, starred);
-                }
-                else {
-                    /* a positional argument */
-                    if (nkeywords) {
-                        if (ndoublestars) {
-                            ast_error(c, chch,
-                                    "positional argument follows "
-                                    "keyword argument unpacking");
-                        }
-                        else {
-                            ast_error(c, chch,
-                                    "positional argument follows "
-                                    "keyword argument");
-                        }
-                        return NULL;
+                    else {
+                        ast_error(c, chch,
+                                "positional argument follows "
+                                "keyword argument");
                     }
-                    e = ast_for_expr(c, chch);
-                    if (!e)
-                        return NULL;
-                    asdl_seq_SET(args, nargs++, e);
+                    return NULL;
                 }
+                e = ast_for_expr(c, chch);
+                if (!e)
+                    return NULL;
+                asdl_seq_SET(args, nargs++, e);
+            }
+            else if (TYPE(chch) == STAR) {
+                /* an iterable argument unpacking */
+                expr_ty starred;
+                if (ndoublestars) {
+                    ast_error(c, chch,
+                            "iterable argument unpacking follows "
+                            "keyword argument unpacking");
+                    return NULL;
+                }
+                e = ast_for_expr(c, CHILD(ch, 1));
+                if (!e)
+                    return NULL;
+                starred = Starred(e, Load, LINENO(chch),
+                        chch->n_col_offset,
+                        c->c_arena);
+                if (!starred)
+                    return NULL;
+                asdl_seq_SET(args, nargs++, starred);
+
             }
             else if (TYPE(chch) == DOUBLESTAR) {
                 /* a keyword argument unpacking */
diff --git a/Python/graminit.c b/Python/graminit.c
index 14ac24f633c..8212b2a5844 100644
--- a/Python/graminit.c
+++ b/Python/graminit.c
@@ -1744,7 +1744,7 @@ static state states_77[3] = {
 static arc arcs_78_0[3] = {
     {26, 1},
     {34, 2},
-    {50, 3},
+    {33, 2},
 };
 static arc arcs_78_1[3] = {
     {164, 3},