diff --git a/src/input/readers/Ascii.cc b/src/input/readers/Ascii.cc
index 9bef57c264..a79121e80a 100644
--- a/src/input/readers/Ascii.cc
+++ b/src/input/readers/Ascii.cc
@@ -51,6 +51,7 @@ Ascii::Ascii(ReaderFrontend *frontend) : ReaderBackend(frontend)
 	{
 	file = 0;
 	mtime = 0;
+	formatter = 0;
 	}
 
 Ascii::~Ascii()
diff --git a/src/logging/writers/Ascii.cc b/src/logging/writers/Ascii.cc
index 9b95639843..a04b30cbae 100644
--- a/src/logging/writers/Ascii.cc
+++ b/src/logging/writers/Ascii.cc
@@ -20,6 +20,7 @@ Ascii::Ascii(WriterFrontend* frontend) : WriterBackend(frontend)
 	fd = 0;
 	ascii_done = false;
 	tsv = false;
+	formatter = 0;
 	}
 
 Ascii::~Ascii()
diff --git a/src/threading/Formatter.h b/src/threading/Formatter.h
index 9f69a3879a..ebdf0c1a87 100644
--- a/src/threading/Formatter.h
+++ b/src/threading/Formatter.h
@@ -76,7 +76,7 @@ public:
 	 * @return The new value, or null on error. Errors must also be
 	 * flagged via the thread.
 	 */
-	virtual threading::Value* ParseValue(string s, string name, TypeTag type, TypeTag subtype = TYPE_ERROR) const = 0;
+	virtual threading::Value* ParseValue(const string& s, const string& name, TypeTag type, TypeTag subtype = TYPE_ERROR) const = 0;
 
 	/**
 	 * Convert an IP address into a string.
diff --git a/src/threading/formatters/Ascii.cc b/src/threading/formatters/Ascii.cc
index c400f8a7ad..3120549f13 100644
--- a/src/threading/formatters/Ascii.cc
+++ b/src/threading/formatters/Ascii.cc
@@ -201,7 +201,7 @@ bool Ascii::Describe(ODesc* desc, threading::Value* val, const string& name) con
 	}
 
 
-threading::Value* Ascii::ParseValue(string s, string name, TypeTag type, TypeTag subtype) const
+threading::Value* Ascii::ParseValue(const string& s, const string& name, TypeTag type, TypeTag subtype) const
 	{
 	if ( s.compare(separators.unset_field) == 0 )  // field is not set...
 		return new threading::Value(type, false);
@@ -214,10 +214,12 @@ threading::Value* Ascii::ParseValue(string s, string name, TypeTag type, TypeTag
 	switch ( type ) {
 	case TYPE_ENUM:
 	case TYPE_STRING:
-		s = get_unescaped_string(s);
-		val->val.string_val.length = s.size();
-		val->val.string_val.data = copy_string(s.c_str());
+		{
+		string unescaped = get_unescaped_string(s);
+		val->val.string_val.length = unescaped.size();
+		val->val.string_val.data = copy_string(unescaped.c_str());
 		break;
+		}
 
 	case TYPE_BOOL:
 		if ( s == "T" )
@@ -263,21 +265,21 @@ threading::Value* Ascii::ParseValue(string s, string name, TypeTag type, TypeTag
 
 	case TYPE_SUBNET:
 		{
-		s = get_unescaped_string(s);
-		size_t pos = s.find("/");
-		if ( pos == s.npos )
+		string unescaped = get_unescaped_string(s);
+		size_t pos = unescaped.find("/");
+		if ( pos == unescaped.npos )
 			{
 			GetThread()->Error(GetThread()->Fmt("Invalid value for subnet: %s", start));
 			goto parse_error;
 			}
 
-		string width_str = s.substr(pos + 1);
+		string width_str = unescaped.substr(pos + 1);
 		uint8_t width = (uint8_t) strtol(width_str.c_str(), &end, 10);
 
 		if ( CheckNumberError(start, end) )
 			goto parse_error;
 
-		string addr = s.substr(0, pos);
+		string addr = unescaped.substr(0, pos);
 
 		val->val.subnet_val.prefix = ParseAddr(addr);
 		val->val.subnet_val.length = width;
@@ -285,9 +287,11 @@ threading::Value* Ascii::ParseValue(string s, string name, TypeTag type, TypeTag
 		}
 
 	case TYPE_ADDR:
-		s = get_unescaped_string(s);
-		val->val.addr_val = ParseAddr(s);
+		{
+		string unescaped = get_unescaped_string(s);
+		val->val.addr_val = ParseAddr(unescaped);
 		break;
+		}
 
 	case TYPE_TABLE:
 	case TYPE_VECTOR:
diff --git a/src/threading/formatters/Ascii.h b/src/threading/formatters/Ascii.h
index ab5e29c1f0..d02b6a89c7 100644
--- a/src/threading/formatters/Ascii.h
+++ b/src/threading/formatters/Ascii.h
@@ -50,7 +50,7 @@ public:
 	virtual bool Describe(ODesc* desc, threading::Value* val, const string& name = "") const;
 	virtual bool Describe(ODesc* desc, int num_fields, const threading::Field* const * fields,
 	                      threading::Value** vals) const;
-	virtual threading::Value* ParseValue(string s, string name, TypeTag type, TypeTag subtype = TYPE_ERROR) const;
+	virtual threading::Value* ParseValue(const string& s, const string& name, TypeTag type, TypeTag subtype = TYPE_ERROR) const;
 
 private:
 	bool CheckNumberError(const char* start, const char* end) const;
diff --git a/src/threading/formatters/JSON.cc b/src/threading/formatters/JSON.cc
index a47de94c0f..17e8808e98 100644
--- a/src/threading/formatters/JSON.cc
+++ b/src/threading/formatters/JSON.cc
@@ -212,7 +212,7 @@ bool JSON::Describe(ODesc* desc, Value* val, const string& name) const
 	return true;
 	}
 
-threading::Value* JSON::ParseValue(string s, string name, TypeTag type, TypeTag subtype) const
+threading::Value* JSON::ParseValue(const string& s, const string& name, TypeTag type, TypeTag subtype) const
 	{
 	GetThread()->Error("JSON formatter does not support parsing yet.");
 	return NULL;
diff --git a/src/threading/formatters/JSON.h b/src/threading/formatters/JSON.h
index 86f3472125..d7859f83fb 100644
--- a/src/threading/formatters/JSON.h
+++ b/src/threading/formatters/JSON.h
@@ -25,7 +25,7 @@ public:
 	virtual bool Describe(ODesc* desc, threading::Value* val, const string& name = "") const;
 	virtual bool Describe(ODesc* desc, int num_fields, const threading::Field* const * fields,
 	                      threading::Value** vals) const;
-	virtual threading::Value* ParseValue(string s, string name, TypeTag type, TypeTag subtype = TYPE_ERROR) const;
+	virtual threading::Value* ParseValue(const string& s, const string& name, TypeTag type, TypeTag subtype = TYPE_ERROR) const;
 
 private:
 	TimeFormat timestamps;