diff --git a/gdb/cli/cli-cmds.c b/gdb/cli/cli-cmds.c
index 2f5ce3e5fff..648005ffdfe 100644
--- a/gdb/cli/cli-cmds.c
+++ b/gdb/cli/cli-cmds.c
@@ -1238,6 +1238,15 @@ list_command (const char *arg, int from_tty)
     {
       event_location_up location = string_to_event_location (&arg1,
 							     current_language);
+
+      /* We know that the ARG string is not empty, yet the attempt to parse
+	 a location from the string consumed no characters.  This most
+	 likely means that the first thing in ARG looks like a location
+	 condition, and so the string_to_event_location call stopped
+	 parsing.  */
+      if (arg1 == arg)
+	error (_("Junk at end of line specification."));
+
       sals = decode_line_1 (location.get (), DECODE_LINE_LIST_MODE,
 			    NULL, NULL, 0);
       filter_sals (sals);
@@ -1286,6 +1295,9 @@ list_command (const char *arg, int from_tty)
 	  event_location_up location
 	    = string_to_event_location (&arg1, current_language);
 
+	  if (*arg1)
+	    error (_("Junk at end of line specification."));
+
 	  std::vector<symtab_and_line> sals_end
 	    = (dummy_beg
 	       ? decode_line_1 (location.get (), DECODE_LINE_LIST_MODE,
diff --git a/gdb/testsuite/gdb.linespec/errors.exp b/gdb/testsuite/gdb.linespec/errors.exp
index 0baef1891a7..e258f6bb98c 100644
--- a/gdb/testsuite/gdb.linespec/errors.exp
+++ b/gdb/testsuite/gdb.linespec/errors.exp
@@ -27,3 +27,15 @@ gdb_test "list c:/foo/bar/baz.c:1" "No source file named c:/foo/bar/baz.c."
 gdb_test "list c:/foo/bar/baz.c" "Function \"c:/foo/bar/baz.c\" not defined."
 gdb_test "list fooc:/foo/bar/baz.c:1" "No source file named fooc."
 gdb_test "list fooc:/foo/bar/baz.c" "No source file named fooc."
+
+# PR cli/28665, gdb/28797
+gdb_test "list task 123" \
+    "Junk at end of line specification\\."
+gdb_test "list if (0)" \
+    "Junk at end of line specification\\."
+gdb_test "list thread 1" \
+    "Junk at end of line specification\\."
+gdb_test "list -force-condition" \
+    "Junk at end of line specification\\."
+gdb_test "list ,," \
+    "Junk at end of line specification\\."