diff --git a/src/box/lua/merger.c b/src/box/lua/merger.c
index 5985c63cebbe69bb5d97b883279b49f108feacd9..fb860dce580aa3cea4b6352eeb1e3d469d7e3ab5 100644
--- a/src/box/lua/merger.c
+++ b/src/box/lua/merger.c
@@ -317,6 +317,7 @@ luaT_merger_new_parse_sources(struct lua_State *L, int idx,
 	}
 
 	/* Save all sources. */
+	int top = lua_gettop(L);
 	for (uint32_t i = 0; i < source_count; ++i) {
 		lua_pushinteger(L, i + 1);
 		lua_gettable(L, idx);
@@ -331,7 +332,7 @@ luaT_merger_new_parse_sources(struct lua_State *L, int idx,
 		}
 		sources[i] = source;
 	}
-	lua_pop(L, source_count);
+	lua_settop(L, top);
 
 	*source_count_ptr = source_count;
 	return sources;
diff --git a/test/box-tap/merger.test.lua b/test/box-tap/merger.test.lua
index ee9eaeaed12e8d5d46a59edf0c6f918682a73472..2d313daa3a51a59a290b173dcbeff638d4eed37e 100755
--- a/test/box-tap/merger.test.lua
+++ b/test/box-tap/merger.test.lua
@@ -550,7 +550,7 @@ end
 
 local test = tap.test('merger')
 test:plan(#bad_source_new_calls + #bad_chunks + #bad_merger_new_calls +
-    #bad_merger_select_calls + 6 + #schemas * 48)
+    #bad_merger_select_calls + 7 + #schemas * 48)
 
 -- For collations.
 box.cfg{}
@@ -765,4 +765,13 @@ for _, input_type in ipairs({'buffer', 'table', 'tuple'}) do
     end
 end
 
+-- merger.new(kd, {}) -- pass zero amount of sources.
+test:test('no sources', function(test)
+    test:plan(1)
+
+    local m = merger.new(key_def, {})
+    local res = m:select()
+    test:is_deeply(res, {})
+end)
+
 os.exit(test:check() and 0 or 1)