diff --git a/gir.js b/gir.js
index 5662a83..18c783d 100644
--- a/gir.js
+++ b/gir.js
@@ -705,8 +705,8 @@ function runVM(state, maxCycles = null) {
 						memory.set(index, 0);
 					}
 					let old = memory.get(index);
-					memory.set(index, old +
-						multiplier * change);
+					let value = old + multiplier * change;
+					memory.set(index, value & 0xff);
 				}
 
 				ip++;
@@ -972,10 +972,12 @@ function ircbotRun(program, input, maxCycles = 400000) {
 		// Find min and max of the existant array indinces, since
 		// there is no good way to easily get them and we need them
 		// for the output
-		let min = Array.from(result.state.memory.keys()).reduce(
-			(x, y) => Math.min(x, y));
-		let max = Array.from(result.state.memory.keys()).reduce(
-			(x, y) => Math.max(x, y));
+		// Default to both being set to tapeHead, because that way
+		// even if there are no indices we can get values that
+		// the rest of the code can work with
+		let memoryIndices = Array.from(result.state.memory.keys());
+		let min = memoryIndices.reduce(Math.min, tapeHead);
+		let max = memoryIndices.reduce(Math.max, tapeHead);
 
 		// Get 15 cells of context on each side of tape head
 		// Exception is if max or min comes up before that, in which