diff --git a/src/flow.c b/src/flow.c
index e00071e..9c4455e 100644
--- a/src/flow.c
+++ b/src/flow.c
@@ -48,7 +48,7 @@ void flow_forloop(struct for_loop *loop)
 	// switching input makes us lose GotByte. But we know it's '}' anyway!
 	// set up new input
 	loop_input = *Input_now;	// copy current input structure into new
-	loop_input.source_is_ram = TRUE;	// set new byte source
+	loop_input.source = INPUTSRC_RAM;	// set new byte source
 	// remember old input
 	outer_input = Input_now;
 	// activate new input
@@ -163,7 +163,7 @@ void flow_do_while(struct do_while *loop)
 
 	// set up new input
 	loop_input = *Input_now;	// copy current input structure into new
-	loop_input.source_is_ram = TRUE;	// set new byte source
+	loop_input.source = INPUTSRC_RAM;	// set new byte source
 	// remember old input
 	outer_input = Input_now;
 	// activate new input (not useable yet, as pointer and
diff --git a/src/input.c b/src/input.c
index 80f940a..5561954 100644
--- a/src/input.c
+++ b/src/input.c
@@ -47,7 +47,7 @@ void Input_new_file(const char *filename, FILE *fd)
 {
 	Input_now->original_filename	= filename;
 	Input_now->line_number		= 1;
-	Input_now->source_is_ram	= FALSE;
+	Input_now->source		= INPUTSRC_FILE;
 	Input_now->state		= INPUTSTATE_NORMAL;
 	Input_now->src.fd		= fd;
 }
@@ -257,10 +257,16 @@ char GetByte(void)
 		// high-level format
 		// Otherwise, the source is a file. This means we will call
 		// GetFormatted() which will do a shit load of conversions.
-		if (Input_now->source_is_ram)
+		switch (Input_now->source) {
+		case INPUTSRC_RAM:
 			GotByte = *(Input_now->src.ram_ptr++);
-		else
+			break;
+		case INPUTSRC_FILE:
 			GotByte = get_processed_from_file();
+			break;
+		default:
+			Bug_found("InvalidInputSrc", Input_now->source);	// FIXME - add to docs
+		}
 //		// if start-of-line was read, increment line counter and repeat
 //		if (GotByte != CHAR_SOL)
 //			return GotByte;
@@ -278,12 +284,13 @@ char GetQuotedByte(void)
 {
 	int	from_file;	// must be an int to catch EOF
 
-	// if byte source is RAM, then no conversion is necessary,
-	// because in RAM the source already has high-level format
-	if (Input_now->source_is_ram) {
+	switch (Input_now->source) {
+	case INPUTSRC_RAM:
+		// if byte source is RAM, then no conversion is necessary,
+		// because in RAM the source already has high-level format
 		GotByte = *(Input_now->src.ram_ptr++);
-	// Otherwise, the source is a file.
-	} else {
+		break;
+	case INPUTSRC_FILE:
 		// fetch a fresh byte from the current source file
 		from_file = getc(Input_now->src.fd);
 		IF_WANTED_REPORT_SRCCHAR(from_file);
@@ -306,7 +313,9 @@ char GetQuotedByte(void)
 		default:
 			GotByte = from_file;
 		}
-
+		break;
+	default:
+		Bug_found("InvalidInputSrc", Input_now->source);	// FIXME - add to docs!
 	}
 	// now check for end of statement
 	if (GotByte == CHAR_EOS)
diff --git a/src/input.h b/src/input.h
index 9d9b7ac..0224d58 100644
--- a/src/input.h
+++ b/src/input.h
@@ -25,10 +25,14 @@ enum inputstate {
 	INPUTSTATE_EOB,		// send end-of-block after end-of-statement
 	INPUTSTATE_EOF,		// send end-of-file after end-of-statement
 };
+enum inputsrc {
+	INPUTSRC_FILE,
+	INPUTSRC_RAM
+};
 struct input {
 	const char	*original_filename;	// during RAM reads, too
 	int		line_number;	// in file (on RAM reads, too)
-	boolean		source_is_ram;	// TRUE if RAM, FALSE if file	(TODO - change to enum)
+	enum inputsrc	source;
 	enum inputstate	state;	// state of input
 	union {
 		FILE	*fd;		// file descriptor
diff --git a/src/macro.c b/src/macro.c
index 92a106e..35b5783 100644
--- a/src/macro.c
+++ b/src/macro.c
@@ -294,7 +294,7 @@ void Macro_parse_call(void)	// Now GotByte = dot or first char of macro name
 		// set up new input
 		new_input.original_filename = actual_macro->def_filename;
 		new_input.line_number = actual_macro->def_line_number;
-		new_input.source_is_ram = TRUE;
+		new_input.source = INPUTSRC_RAM;
 		new_input.state = INPUTSTATE_NORMAL;	// FIXME - fix others!
 		new_input.src.ram_ptr = actual_macro->parameter_list;
 		// remember old input
diff --git a/src/version.h b/src/version.h
index c5a509b..2caf9e8 100644
--- a/src/version.h
+++ b/src/version.h
@@ -9,7 +9,7 @@
 
 #define RELEASE		"0.96.5"	// update before release	FIXME
 #define CODENAME	"Fenchurch"	// update before release
-#define CHANGE_DATE	"18 May"	// update before release	FIXME
+#define CHANGE_DATE	"19 May"	// update before release	FIXME
 #define CHANGE_YEAR	"2020"		// update before release
 //#define HOME_PAGE	"http://home.pages.de/~mac_bacon/smorbrod/acme/"
 #define HOME_PAGE	"http://sourceforge.net/p/acme-crossass/"	// FIXME