diff --git a/neotron-bmc-commands/Cargo.toml b/neotron-bmc-commands/Cargo.toml
index a8784e3..5cd49ee 100644
--- a/neotron-bmc-commands/Cargo.toml
+++ b/neotron-bmc-commands/Cargo.toml
@@ -4,7 +4,7 @@ edition = "2021"
 license = "BlueOak-1.0.0"
 name = "neotron-bmc-commands"
 repository = "https://github.com/neotron-compute/neotron-bmc"
-version = "0.1.0"
+version = "0.2.0"
 homepage = "https://github.com/neotron-compute"
 readme = "README.md"
 
diff --git a/neotron-bmc-commands/README.md b/neotron-bmc-commands/README.md
index df85bf7..e6f736d 100644
--- a/neotron-bmc-commands/README.md
+++ b/neotron-bmc-commands/README.md
@@ -217,17 +217,17 @@ should set the other three registers (if required) before setting this register.
 There is no way to know when the tone is ended; the host should keep track of
 the duration it set and wait the appropriate period of time.
 
-### Address 0x71 - Speaker Tone Period (Low)
-
-Sets the lower 8 bits of the tone period. See *Speaker Tone Period (High)* for details.
-
-### Address 0x72 - Speaker Tone Period (High)
+### Address 0x71 - Speaker Tone Period (High)
 
 Sets the upper 8 bits of the tone period. This is the inverse of frequency, in
 48 kHz units. A value of `48000 / 440 = 109 = 0x006D` will give you a
 Concert-pitch A (440 Hz). Write that value as `0x00` in the high register and
 `0x6D` in the low register.
 
+### Address 0x72 - Speaker Tone Period (Low)
+
+Sets the lower 8 bits of the tone period. See *Speaker Tone Period (High)* for details.
+
 ### Address 0x73 - Speaker Tone Duty Cycle
 
 Sets the duty-cycle of the speaker tone. A value of 127 is 50:50 (a square wave).
diff --git a/neotron-bmc-commands/src/lib.rs b/neotron-bmc-commands/src/lib.rs
index 3e63262..821a89c 100644
--- a/neotron-bmc-commands/src/lib.rs
+++ b/neotron-bmc-commands/src/lib.rs
@@ -139,16 +139,16 @@ pub enum Command {
 	/// * Length: 1
 	/// * Mode: R/W
 	SpeakerDuration = 0x70,
-	/// # Speaker Period (Low byte)
-	/// Low byte of 16-bit period (in 48kHz ticks)
+	/// # Speaker Tone Period (High byte)
+	/// High byte of 16-bit period (in 48kHz ticks)
 	/// * Length: 1
 	/// * Mode: R/W
-	SpeakerPeriodLow = 0x71,
-	/// # Speaker Period (High byte)
-	/// High byte of 16-bit period (in 48kHz ticks)
+	SpeakerPeriodHigh = 0x71,
+	/// # Speaker Tone Period (Low byte)
+	/// Low byte of 16-bit period (in 48kHz ticks)
 	/// * Length: 1
 	/// * Mode: R/W
-	SpeakerPeriodHigh = 0x72,
+	SpeakerPeriodLow = 0x72,
 	/// # Speaker Duty Cycle
 	/// Speaker Duty cycle, in 1/255
 	/// * Length: 1
diff --git a/neotron-bmc-pico/Cargo.lock b/neotron-bmc-pico/Cargo.lock
index 0158d1e..2d36697 100644
--- a/neotron-bmc-pico/Cargo.lock
+++ b/neotron-bmc-pico/Cargo.lock
@@ -284,14 +284,14 @@ checksum = "8d5439c4ad607c3c23abf66de8c8bf57ba8adcd1f129e699851a6e43935d339d"
 
 [[package]]
 name = "neotron-bmc-commands"
-version = "0.1.0"
+version = "0.2.0"
 dependencies = [
  "num_enum",
 ]
 
 [[package]]
 name = "neotron-bmc-pico"
-version = "0.5.3"
+version = "0.5.4"
 dependencies = [
  "cortex-m",
  "cortex-m-rtic",
diff --git a/neotron-bmc-pico/Cargo.toml b/neotron-bmc-pico/Cargo.toml
index 7481b6d..3043f91 100644
--- a/neotron-bmc-pico/Cargo.toml
+++ b/neotron-bmc-pico/Cargo.toml
@@ -5,7 +5,7 @@ edition = "2018"
 license = "GPL-3.0-or-later"
 name = "neotron-bmc-pico"
 readme = "README.md"
-version = "0.5.3"
+version = "0.5.4"
 
 [dependencies]
 cortex-m = { version = "0.7.5", features = ["inline-asm", "critical-section-single-core"] }
@@ -17,7 +17,7 @@ heapless= "0.7"
 panic-probe = { version = "0.3", features = ["print-defmt"] }
 stm32f0xx-hal = { version = "0.18", features = ["stm32f030x6", "rt"] }
 neotron-bmc-protocol = { version = "0.1", path = "../neotron-bmc-protocol", features = ["defmt"] }
-neotron-bmc-commands = { version = "0.1", path = "../neotron-bmc-commands" }
+neotron-bmc-commands = { version = "0.2", path = "../neotron-bmc-commands" }
 systick-monotonic = "1.0"
 embedded-hal = "*"
 
diff --git a/neotron-bmc-pico/src/speaker.rs b/neotron-bmc-pico/src/speaker.rs
index 9df3122..cf809e8 100644
--- a/neotron-bmc-pico/src/speaker.rs
+++ b/neotron-bmc-pico/src/speaker.rs
@@ -37,7 +37,7 @@ impl RegisterState {
 	}
 
 	pub fn set_period_high(&mut self, period_high: u8) {
-		self.period = (self.period & 0xff00) | period_high as u16;
+		self.period = (self.period & 0x00ff) | ((period_high as u16) << 8);
 	}
 
 	pub fn period_low(&self) -> u8 {
@@ -45,7 +45,7 @@ impl RegisterState {
 	}
 
 	pub fn set_period_low(&mut self, period_low: u8) {
-		self.period = (self.period() & 0xff) | ((period_low as u16) << 8);
+		self.period = (self.period & 0xff00) | period_low as u16;
 	}
 
 	pub fn duration(&self) -> u16 {