diff --git a/src/emu/debug/debugcpu.c b/src/emu/debug/debugcpu.c
index 52746397fa0..9b8b658f8f2 100644
--- a/src/emu/debug/debugcpu.c
+++ b/src/emu/debug/debugcpu.c
@@ -2753,7 +2753,7 @@ UINT32 device_debug::dasm_wrapped(astring &buffer, offs_t pc)
 
 	// disassemble to our buffer
 	buffer.expand(200);
-	return disassemble(buffer, pc, opbuf, argbuf);
+	return disassemble(buffer.text, pc, opbuf, argbuf);
 }
 
 
diff --git a/src/lib/util/astring.h b/src/lib/util/astring.h
index cb2f450e7fe..7ff236f7f0a 100644
--- a/src/lib/util/astring.h
+++ b/src/lib/util/astring.h
@@ -333,7 +333,7 @@ public:
 	astring &reset() { return cpy(""); }
 	astring &expand(int length) { astring_expand(this, length); return *this; }
 
-	operator char *() { return (this->text[0] != 0) ? this->text : NULL; }
+	operator bool() const { return this->text[0] != 0; }
 	operator const char *() const { return astring_c(this); }
 	const char *cstr() const { return astring_c(this); }
 	int len() const { return astring_len(this); }