diff --git a/src/emu/sound.cpp b/src/emu/sound.cpp
index 1b007a303ea..096695935d9 100644
--- a/src/emu/sound.cpp
+++ b/src/emu/sound.cpp
@@ -163,8 +163,10 @@ float sound_stream::output_gain(int outputnum) const
 //  on a given stream's input
 //-------------------------------------------------
 
-const char *sound_stream::input_name(int inputnum, std::string &str) const
+std::string sound_stream::input_name(int inputnum) const
 {
+	std::string str;
+
 	// start with our device name and tag
 	assert(inputnum >= 0 && inputnum < m_input.size());
 	strprintf(str, "%s '%s': ", m_device.name(), m_device.tag());
@@ -191,7 +193,7 @@ const char *sound_stream::input_name(int inputnum, std::string &str) const
 				}
 		}
 	}
-	return str.c_str();
+	return str;
 }
 
 
diff --git a/src/emu/sound.h b/src/emu/sound.h
index 9480388ac5b..b3584969284 100644
--- a/src/emu/sound.h
+++ b/src/emu/sound.h
@@ -106,7 +106,7 @@ public:
 	attotime sample_period() const { return attotime(0, m_attoseconds_per_sample); }
 	int input_count() const { return m_input.size(); }
 	int output_count() const { return m_output.size(); }
-	const char *input_name(int inputnum, std::string &str) const;
+	std::string input_name(int inputnum) const;
 	device_t *input_source_device(int inputnum) const;
 	int input_source_outputnum(int inputnum) const;
 	float user_gain(int inputnum) const;
diff --git a/src/emu/ui/ui.cpp b/src/emu/ui/ui.cpp
index 61c610d5a0e..8175df2871e 100644
--- a/src/emu/ui/ui.cpp
+++ b/src/emu/ui/ui.cpp
@@ -1872,7 +1872,7 @@ static slider_state *slider_init(running_machine &machine)
 		INT32 maxval = 2000;
 		INT32 defval = 1000;
 
-		info.stream->input_name(info.inputnum, str);
+		str.assign(info.stream->input_name(info.inputnum));
 		str.append(" Volume");
 		*tailptr = slider_alloc(machine, str.c_str(), 0, defval, maxval, 20, slider_mixervol, (void *)(FPTR)item);
 		tailptr = &(*tailptr)->next;