diff --git a/simulator/simulator/rusEfiFunctionalTest.cpp b/simulator/simulator/rusEfiFunctionalTest.cpp
index f2dbca1e95..b69725b58d 100644
--- a/simulator/simulator/rusEfiFunctionalTest.cpp
+++ b/simulator/simulator/rusEfiFunctionalTest.cpp
@@ -52,6 +52,12 @@ float getMap(void) {
 	return getRawMap();
 }
 
+static void assertString(const char*actual, const char *expected) {
+	if (strcmp(actual, expected) != 0) {
+		firmwareError(OBD_PCM_Processor_Fault, "chprintf test: got %s while %s", actual, expected);
+	}
+}
+
 static void runChprintfTest() {
 	static MemoryStream testStream;
 	static char testBuffer[200];
@@ -63,21 +69,26 @@ static void runChprintfTest() {
 	chprintf((BaseSequentialStream*)&testStream, "%f/%.4f/%.4f", 0.239f, 239.932, 0.1234);
 	testStream.buffer[testStream.eos] = 0;
 
-#define FLOAT_STRING_EXPECTED "0.23/239.9320/0.1234"
-	if (strcmp(FLOAT_STRING_EXPECTED, testBuffer) != 0) {
-		firmwareError(OBD_PCM_Processor_Fault, "chprintf test: got %s while %s", testBuffer, FLOAT_STRING_EXPECTED);
-	}
+	assertString(testBuffer, "0.23/239.9320/0.1234");
+
 
 	{
 		LoggingWithStorage testLogging("test");
 		appendFloat(&testLogging, 1.23, 5);
 		appendFloat(&testLogging, 1.234, 2);
+		assertString(testLogging.buffer, "1.230001.23");
 
-#define FLOAT_STRING_EXPECTED2 "1.230001.23"
-		if (strcmp(FLOAT_STRING_EXPECTED2, testLogging.buffer) != 0) {
-			firmwareError(OBD_PCM_Processor_Fault, "chprintf test2: got %s while %s", testLogging.buffer, FLOAT_STRING_EXPECTED2);
-		}
+	}
 
+	{
+		LoggingWithStorage testLogging("test");
+		appendFloat(&testLogging, -1.23, 5);
+		assertString(testLogging.buffer, "-1.23000");
+	}
+	{
+		LoggingWithStorage testLogging("test");
+		appendPrintf(&testLogging, "a%fb", -1.2);
+		assertString(testLogging.buffer, "a-1.20b");
 	}
 
 }