diff --git a/arrow-libs/fx/arrow-fx-stm/src/commonMain/kotlin/arrow/fx/stm/STM.kt b/arrow-libs/fx/arrow-fx-stm/src/commonMain/kotlin/arrow/fx/stm/STM.kt
index aa5ca900e0c..895be245622 100644
--- a/arrow-libs/fx/arrow-fx-stm/src/commonMain/kotlin/arrow/fx/stm/STM.kt
+++ b/arrow-libs/fx/arrow-fx-stm/src/commonMain/kotlin/arrow/fx/stm/STM.kt
@@ -55,7 +55,7 @@ import arrow.fx.stm.internal.lookupHamtWithHash
  *
  * fun STM.withdraw(acc: TVar<Int>, amount: Int): Unit {
  *   val current = acc.read()
- *   if (current - amount >= 0) acc.write(current + amount)
+ *   if (current - amount >= 0) acc.write(current - amount)
  *   else throw IllegalStateException("Not enough money in the account!")
  * }
  * //sampleEnd
@@ -112,7 +112,7 @@ import arrow.fx.stm.internal.lookupHamtWithHash
  *
  * fun STM.withdraw(acc: TVar<Int>, amount: Int): Unit {
  *   val current = acc.read()
- *   if (current - amount >= 0) acc.write(current + amount)
+ *   if (current - amount >= 0) acc.write(current - amount)
  *   else retry() // we now retry if there is not enough money in the account
  *   // this can also be achieved by using `check(current - amount >= 0); acc.write(it + amount)`
  * }
diff --git a/arrow-libs/fx/arrow-fx-stm/src/jvmTest/kotlin/examples/example-stm-01.kt b/arrow-libs/fx/arrow-fx-stm/src/jvmTest/kotlin/examples/example-stm-01.kt
index c74156a49ce..c48332f9f87 100644
--- a/arrow-libs/fx/arrow-fx-stm/src/jvmTest/kotlin/examples/example-stm-01.kt
+++ b/arrow-libs/fx/arrow-fx-stm/src/jvmTest/kotlin/examples/example-stm-01.kt
@@ -18,7 +18,7 @@ fun STM.deposit(acc: TVar<Int>, amount: Int): Unit {
 
 fun STM.withdraw(acc: TVar<Int>, amount: Int): Unit {
   val current = acc.read()
-  if (current - amount >= 0) acc.write(current + amount)
+  if (current - amount >= 0) acc.write(current - amount)
   else throw IllegalStateException("Not enough money in the account!")
 }
 
diff --git a/arrow-libs/fx/arrow-fx-stm/src/jvmTest/kotlin/examples/example-stm-02.kt b/arrow-libs/fx/arrow-fx-stm/src/jvmTest/kotlin/examples/example-stm-02.kt
index bdeaf829b0b..af8152800bb 100644
--- a/arrow-libs/fx/arrow-fx-stm/src/jvmTest/kotlin/examples/example-stm-02.kt
+++ b/arrow-libs/fx/arrow-fx-stm/src/jvmTest/kotlin/examples/example-stm-02.kt
@@ -21,7 +21,7 @@ fun STM.deposit(acc: TVar<Int>, amount: Int): Unit {
 
 fun STM.withdraw(acc: TVar<Int>, amount: Int): Unit {
   val current = acc.read()
-  if (current - amount >= 0) acc.write(current + amount)
+  if (current - amount >= 0) acc.write(current - amount)
   else retry() // we now retry if there is not enough money in the account
   // this can also be achieved by using `check(current - amount >= 0); acc.write(it + amount)`
 }