diff --git a/library/api/api.txt b/library/api/api.txt
index 37699ef..77c2e08 100644
--- a/library/api/api.txt
+++ b/library/api/api.txt
@@ -15,6 +15,7 @@ package me.saket.bytesize {
     method public inline operator long plus(me.saket.bytesize.ByteSize other);
     method public inline long times(Number other);
     method public inline String toString();
+    method public operator long unaryMinus();
     property public inline long inWholeBytes;
     property public final inline long inWholeGibibytes;
     property public final inline long inWholeKibibytes;
@@ -32,6 +33,7 @@ package me.saket.bytesize {
     method public operator me.saket.bytesize.ByteSize minus(me.saket.bytesize.ByteSize other);
     method public operator me.saket.bytesize.ByteSize plus(me.saket.bytesize.ByteSize other);
     method public operator me.saket.bytesize.ByteSize times(Number other);
+    method public operator me.saket.bytesize.ByteSize unaryMinus();
     property public abstract long inWholeBytes;
   }
 
@@ -57,6 +59,7 @@ package me.saket.bytesize {
     method public inline long plus(me.saket.bytesize.ByteSize other);
     method public inline long times(Number other);
     method public inline String toString();
+    method public operator long unaryMinus();
     property public inline long inWholeBits;
     property public inline long inWholeBytes;
     property public final inline long inWholeGigabits;
@@ -82,6 +85,7 @@ package me.saket.bytesize {
     method public inline operator long plus(me.saket.bytesize.ByteSize other);
     method public inline long times(Number other);
     method public inline String toString();
+    method public operator long unaryMinus();
     property public inline long inWholeBytes;
     property public final inline long inWholeGigabytes;
     property public final inline long inWholeKilobytes;
diff --git a/library/src/commonMain/kotlin/me/saket/bytesize/BinaryByteSize.kt b/library/src/commonMain/kotlin/me/saket/bytesize/BinaryByteSize.kt
index 8517e45..c316e57 100644
--- a/library/src/commonMain/kotlin/me/saket/bytesize/BinaryByteSize.kt
+++ b/library/src/commonMain/kotlin/me/saket/bytesize/BinaryByteSize.kt
@@ -73,6 +73,9 @@ value class BinaryByteSize(
   override inline fun div(other: Number): BinaryByteSize =
     BinaryByteSize(commonDiv(other))
 
+  override operator fun unaryMinus(): BinaryByteSize =
+    BinaryByteSize(-bytes)
+
   override inline fun compareTo(other: ByteSize): Int =
     commonCompareTo(other)
 
diff --git a/library/src/commonMain/kotlin/me/saket/bytesize/ByteSize.kt b/library/src/commonMain/kotlin/me/saket/bytesize/ByteSize.kt
index 8d8f4fc..25f7631 100644
--- a/library/src/commonMain/kotlin/me/saket/bytesize/ByteSize.kt
+++ b/library/src/commonMain/kotlin/me/saket/bytesize/ByteSize.kt
@@ -22,6 +22,7 @@ sealed interface ByteSize : Comparable<ByteSize> {
   operator fun times(other: Number): ByteSize
   operator fun div(other: ByteSize): Double
   operator fun div(other: Number): ByteSize
+  operator fun unaryMinus(): ByteSize
 }
 
 inline operator fun Number.times(other: ByteSize): ByteSize =
diff --git a/library/src/commonMain/kotlin/me/saket/bytesize/DecimalBitSize.kt b/library/src/commonMain/kotlin/me/saket/bytesize/DecimalBitSize.kt
index bf03907..cdb6d79 100644
--- a/library/src/commonMain/kotlin/me/saket/bytesize/DecimalBitSize.kt
+++ b/library/src/commonMain/kotlin/me/saket/bytesize/DecimalBitSize.kt
@@ -83,6 +83,9 @@ value class DecimalBitSize(
     return DecimalBitSize(bits = commonDiv(other))
   }
 
+  override operator fun unaryMinus(): DecimalBitSize =
+    DecimalBitSize(-bits)
+
   override inline fun compareTo(other: ByteSize): Int {
     return commonCompareTo(other)
   }
diff --git a/library/src/commonMain/kotlin/me/saket/bytesize/DecimalByteSize.kt b/library/src/commonMain/kotlin/me/saket/bytesize/DecimalByteSize.kt
index d84b096..9952803 100644
--- a/library/src/commonMain/kotlin/me/saket/bytesize/DecimalByteSize.kt
+++ b/library/src/commonMain/kotlin/me/saket/bytesize/DecimalByteSize.kt
@@ -73,6 +73,9 @@ value class DecimalByteSize(
   override inline fun div(other: Number): DecimalByteSize =
     DecimalByteSize(commonDiv(other))
 
+  override operator fun unaryMinus(): DecimalByteSize =
+    DecimalByteSize(-bytes)
+
   override inline fun compareTo(other: ByteSize): Int =
     commonCompareTo(other)
 
diff --git a/library/src/commonTest/kotlin/me/saket/bytesize/BinaryByteSizeTest.kt b/library/src/commonTest/kotlin/me/saket/bytesize/BinaryByteSizeTest.kt
index 2828df6..fbd6048 100644
--- a/library/src/commonTest/kotlin/me/saket/bytesize/BinaryByteSizeTest.kt
+++ b/library/src/commonTest/kotlin/me/saket/bytesize/BinaryByteSizeTest.kt
@@ -115,4 +115,12 @@ class BinaryByteSizeTest {
       BinaryByteSize(500.50)
     }.hasMessage(BytePrecisionLossErrorMessage)
   }
+
+  @Test fun unary_minus() {
+    val twelve = 12.binaryBytes
+    val negativeTwelve = -twelve
+    assertThat(negativeTwelve).isEqualTo((-12).binaryBytes)
+    val positiveTwelve = -negativeTwelve
+    assertThat(positiveTwelve).isEqualTo(twelve)
+  }
 }
diff --git a/library/src/commonTest/kotlin/me/saket/bytesize/DecimalBitSizeTest.kt b/library/src/commonTest/kotlin/me/saket/bytesize/DecimalBitSizeTest.kt
index 42cf20a..0b949e8 100644
--- a/library/src/commonTest/kotlin/me/saket/bytesize/DecimalBitSizeTest.kt
+++ b/library/src/commonTest/kotlin/me/saket/bytesize/DecimalBitSizeTest.kt
@@ -113,4 +113,12 @@ class DecimalBitSizeTest {
       DecimalBitSize(123.45)
     }.hasMessage(BitPrecisionLossErrorMessage)
   }
+
+  @Test fun unary_minus() {
+    val twelve = 12.decimalBits
+    val negativeTwelve = -twelve
+    assertThat(negativeTwelve).isEqualTo((-12).decimalBits)
+    val positiveTwelve = -negativeTwelve
+    assertThat(positiveTwelve).isEqualTo(twelve)
+  }
 }
diff --git a/library/src/commonTest/kotlin/me/saket/bytesize/DecimalByteSizeTest.kt b/library/src/commonTest/kotlin/me/saket/bytesize/DecimalByteSizeTest.kt
index a86f3bb..b57fb9f 100644
--- a/library/src/commonTest/kotlin/me/saket/bytesize/DecimalByteSizeTest.kt
+++ b/library/src/commonTest/kotlin/me/saket/bytesize/DecimalByteSizeTest.kt
@@ -160,4 +160,12 @@ class DecimalByteSizeTest {
       DecimalByteSize(500.50)
     }.hasMessage(BytePrecisionLossErrorMessage)
   }
+
+  @Test fun unary_minus() {
+    val twelve = 12.decimalBytes
+    val negativeTwelve = -twelve
+    assertThat(negativeTwelve).isEqualTo((-12).decimalBytes)
+    val positiveTwelve = -negativeTwelve
+    assertThat(positiveTwelve).isEqualTo(twelve)
+  }
 }