diff --git a/core/src/consensus.rs b/core/src/consensus.rs
index 4cae47dcd..804e5cd03 100644
--- a/core/src/consensus.rs
+++ b/core/src/consensus.rs
@@ -62,29 +62,31 @@ pub const COINBASE_MATURITY: u64 = DAY_HEIGHT;
 /// function of block height (time). Starts at 90% losing a percent
 /// approximately every week. Represented as an integer between 0 and 100.
 pub fn secondary_pow_ratio(height: u64) -> u64 {
-	if global::is_mainnet() {
-		90u64.saturating_sub(height / (2 * YEAR_HEIGHT / 90))
-	} else {
+	if global::is_testnet() {
 		if height < T4_CUCKAROO_HARDFORK {
 			// Maintaining pre hardfork testnet4 behavior
 			90u64.saturating_sub(height / WEEK_HEIGHT)
 		} else {
 			90u64.saturating_sub(height / (2 * YEAR_HEIGHT / 90))
 		}
+	} else {
+		// Mainnet (or testing mainnet code).
+		90u64.saturating_sub(height / (2 * YEAR_HEIGHT / 90))
 	}
 }
 
 /// The AR scale damping factor to use. Dependent on block height
 /// to account for pre HF behavior on testnet4.
 fn ar_scale_damp_factor(height: u64) -> u64 {
-	if global::is_mainnet() {
-		AR_SCALE_DAMP_FACTOR
-	} else {
+	if global::is_testnet() {
 		if height < T4_CUCKAROO_HARDFORK {
 			DIFFICULTY_DAMP_FACTOR
 		} else {
 			AR_SCALE_DAMP_FACTOR
 		}
+	} else {
+		// Mainnet (or testing mainnet code).
+		AR_SCALE_DAMP_FACTOR
 	}
 }
 
@@ -332,7 +334,8 @@ where
 /// the hardfork.
 fn ar_count(height: u64, diff_data: &[HeaderInfo]) -> u64 {
 	let mut to_skip = 1;
-	if !global::is_mainnet() && height < T4_CUCKAROO_HARDFORK {
+	if global::is_testnet() && height < T4_CUCKAROO_HARDFORK {
+		// Maintain behavior of testnet4 pre-HF.
 		to_skip = 0;
 	}
 	100 * diff_data
diff --git a/core/src/core/transaction.rs b/core/src/core/transaction.rs
index b046453fb..10ba740dd 100644
--- a/core/src/core/transaction.rs
+++ b/core/src/core/transaction.rs
@@ -1295,14 +1295,14 @@ pub fn kernel_sig_msg(
 	lock_height: u64,
 	features: KernelFeatures,
 ) -> Result<secp::Message, Error> {
-	let msg = if global::is_mainnet() {
-		let hash = (fee, lock_height, features).hash();
-		secp::Message::from_slice(&hash.as_bytes())?
-	} else {
+	let msg = if global::is_testnet() {
 		let mut bytes = [0; 32];
 		BigEndian::write_u64(&mut bytes[16..24], fee);
 		BigEndian::write_u64(&mut bytes[24..], lock_height);
 		secp::Message::from_slice(&bytes)?
+	} else {
+		let hash = (fee, lock_height, features).hash();
+		secp::Message::from_slice(&hash.as_bytes())?
 	};
 	Ok(msg)
 }
diff --git a/core/src/global.rs b/core/src/global.rs
index 30a38374d..153bea402 100644
--- a/core/src/global.rs
+++ b/core/src/global.rs
@@ -284,7 +284,8 @@ pub fn is_user_testing_mode() -> bool {
 	ChainTypes::UserTesting == *param_ref
 }
 
-/// Are we in production mode (a live public network)?
+/// Are we in production mode?
+/// Production defined as a live public network, testnet[n] or mainnet.
 pub fn is_production_mode() -> bool {
 	let param_ref = CHAIN_TYPE.read();
 	ChainTypes::Testnet1 == *param_ref
@@ -294,10 +295,13 @@ pub fn is_production_mode() -> bool {
 		|| ChainTypes::Mainnet == *param_ref
 }
 
-/// Are we in mainnet?
-pub fn is_mainnet() -> bool {
+/// Are we in one of our (many) testnets?
+pub fn is_testnet() -> bool {
 	let param_ref = CHAIN_TYPE.read();
-	ChainTypes::Mainnet == *param_ref
+	ChainTypes::Testnet1 == *param_ref
+		|| ChainTypes::Testnet2 == *param_ref
+		|| ChainTypes::Testnet3 == *param_ref
+		|| ChainTypes::Testnet4 == *param_ref
 }
 
 /// Helper function to get a nonce known to create a valid POW on
diff --git a/core/tests/consensus.rs b/core/tests/consensus.rs
index 1dc59a94c..8178c456f 100644
--- a/core/tests/consensus.rs
+++ b/core/tests/consensus.rs
@@ -384,9 +384,18 @@ fn next_target_adjustment() {
 	let diff_min = Difficulty::min();
 
 	// Check we don't get stuck on difficulty <= MIN_DIFFICULTY (at 4x faster blocks at least)
-	let mut hi = HeaderInfo::from_diff_scaling(diff_min, MIN_DIFFICULTY as u32);
+	let mut hi = HeaderInfo::from_diff_scaling(diff_min, AR_SCALE_DAMP_FACTOR as u32);
 	hi.is_secondary = false;
-	let hinext = next_difficulty(1, repeat(15, hi.clone(), DIFFICULTY_ADJUST_WINDOW, None));
+	let hinext = next_difficulty(
+		1,
+		repeat(
+			BLOCK_TIME_SEC / 4,
+			hi.clone(),
+			DIFFICULTY_ADJUST_WINDOW,
+			None,
+		),
+	);
+
 	assert_ne!(hinext.difficulty, diff_min);
 
 	// Check we don't get stuck on scale MIN_DIFFICULTY, when primary frequency is too high
@@ -476,7 +485,7 @@ fn test_secondary_pow_ratio() {
 	// Tests for mainnet chain type.
 	{
 		global::set_mining_mode(global::ChainTypes::Mainnet);
-		assert_eq!(global::is_mainnet(), true);
+		assert_eq!(global::is_testnet(), false);
 
 		assert_eq!(secondary_pow_ratio(1), 90);
 		assert_eq!(secondary_pow_ratio(89), 90);
@@ -518,7 +527,7 @@ fn test_secondary_pow_ratio() {
 	// Tests for testnet4 chain type (covers pre and post hardfork).
 	{
 		global::set_mining_mode(global::ChainTypes::Testnet4);
-		assert_eq!(global::is_mainnet(), false);
+		assert_eq!(global::is_testnet(), true);
 
 		assert_eq!(secondary_pow_ratio(1), 90);
 		assert_eq!(secondary_pow_ratio(89), 90);
@@ -566,7 +575,7 @@ fn test_secondary_pow_scale() {
 	// testnet4 testing
 	{
 		global::set_mining_mode(global::ChainTypes::Testnet4);
-		assert_eq!(global::is_mainnet(), false);
+		assert_eq!(global::is_testnet(), true);
 
 		// all primary, factor should increase so it becomes easier to find a high
 		// difficulty block
@@ -640,7 +649,7 @@ fn test_secondary_pow_scale() {
 	// mainnet testing
 	{
 		global::set_mining_mode(global::ChainTypes::Mainnet);
-		assert_eq!(global::is_mainnet(), true);
+		assert_eq!(global::is_testnet(), false);
 
 		// all primary, factor should increase so it becomes easier to find a high
 		// difficulty block