diff --git a/tests/test-config.c b/tests/test-config.c
index da0314d6..68fa2767 100644
--- a/tests/test-config.c
+++ b/tests/test-config.c
@@ -623,6 +623,8 @@ test_section_colors(void)
                    &conf.colors.table[i]);
     }
 
+    test_invalid_key(&ctx, &parse_section_colors, "256");
+
     /* TODO: alpha (float in range 0-1, converted to uint16_t) */
     /* TODO: jump-labels (two colors) */
     /* TODO: scrollback-indicator (two colors) */