diff --git a/benchmark/bench_plot_test.go b/benchmark/bench_plot_test.go
index 0285894..e12f76d 100644
--- a/benchmark/bench_plot_test.go
+++ b/benchmark/bench_plot_test.go
@@ -95,7 +95,7 @@ func TestBenchmarkAndPlot(t *testing.T) {
 			}
 
 			// render graph into file
-			outputFilename := path.Join("out", fmt.Sprintf("%s_memory:%v.png", getFuncName(benchFunc), isMemoryDB))
+			outputFilename := path.Join("out", fmt.Sprintf("%s_memory_%v.png", getFuncName(benchFunc), isMemoryDB))
 			if err := graph.Render(outputFilename); err != nil {
 				log.Fatal(err)
 			}
diff --git a/benchmark/out/benchmarkInsert_memory:false.png b/benchmark/out/benchmarkInsert_memory_false.png
similarity index 100%
rename from benchmark/out/benchmarkInsert_memory:false.png
rename to benchmark/out/benchmarkInsert_memory_false.png
diff --git a/benchmark/out/benchmarkInsert_memory:true.png b/benchmark/out/benchmarkInsert_memory_true.png
similarity index 100%
rename from benchmark/out/benchmarkInsert_memory:true.png
rename to benchmark/out/benchmarkInsert_memory_true.png
diff --git a/benchmark/out/benchmarkSelect_memory:false.png b/benchmark/out/benchmarkSelect_memory_false.png
similarity index 100%
rename from benchmark/out/benchmarkSelect_memory:false.png
rename to benchmark/out/benchmarkSelect_memory_false.png
diff --git a/benchmark/out/benchmarkSelect_memory:true.png b/benchmark/out/benchmarkSelect_memory_true.png
similarity index 100%
rename from benchmark/out/benchmarkSelect_memory:true.png
rename to benchmark/out/benchmarkSelect_memory_true.png