diff --git a/source/Sagan-GemStone-Tests/GemStoneRepositoryProviderTest.class.st b/source/Sagan-GemStone-Tests/GemStoneRepositoryProviderTest.class.st
index a788605..ac3babe 100644
--- a/source/Sagan-GemStone-Tests/GemStoneRepositoryProviderTest.class.st
+++ b/source/Sagan-GemStone-Tests/GemStoneRepositoryProviderTest.class.st
@@ -40,14 +40,10 @@ GemStoneRepositoryProviderTest >> testExceptionsAbortTransactionsUntilHandled [
 	self assert: self extraterrestrials findAll isEmpty.
 
 	self extraterrestrials transact: [
+		[
 		self extraterrestrials store: self silvesterStallone.
 		self assertTheOnlyOneInTheRepositoryIsSilvesterStallone.
-
-		[
-		self extraterrestrials transact: [
-			self extraterrestrials store: self johnTravolta.
-			1 / 0
-			]
+		1 / 0
 		]
 			on: ZeroDivide
 			do: [ :ex | ex return ]
@@ -56,27 +52,6 @@ GemStoneRepositoryProviderTest >> testExceptionsAbortTransactionsUntilHandled [
 	self assertTheOnlyOneInTheRepositoryIsSilvesterStallone
 ]
 
-{ #category : 'tests' }
-GemStoneRepositoryProviderTest >> testNestedTransactions [
-
-	self assert: self extraterrestrials findAll isEmpty.
-
-	self extraterrestrials transact: [
-		self extraterrestrials store: self silvesterStallone.
-		self assertTheOnlyOneInTheRepositoryIsSilvesterStallone.
-
-		System abortTransaction.
-		self assert: self extraterrestrials findAll isEmpty.
-		self extraterrestrials transact: [ self extraterrestrials store: self johnTravolta ]
-		].
-
-	self withTheOnlyOneIn: self extraterrestrials findAll do: [ :extraterrestrial |
-		self
-			assert: extraterrestrial firstName equals: 'John';
-			assert: extraterrestrial lastName equals: 'Travolta'
-		]
-]
-
 { #category : 'tests' }
 GemStoneRepositoryProviderTest >> testQueryReturningBeforeAllIndexedResultsAreRead [
 
@@ -340,54 +315,55 @@ GemStoneRepositoryProviderTest >> testStreamQueryResults [
 { #category : 'tests' }
 GemStoneRepositoryProviderTest >> testTransactionLevel [
 
-	| initialLevel |
+	| baseLevel |
 
-	initialLevel := System transactionLevel.
-	self assert: initialLevel >= 0.
+	baseLevel := System transactionLevel.
 
 	self extraterrestrials transact: [
-		self assert: System transactionLevel equals: initialLevel + 1.
-		self extraterrestrials transact: [ self assert: System transactionLevel equals: initialLevel + 2 ].
-		self assert: System transactionLevel equals: initialLevel + 1
-		].
-	self assert: System transactionLevel equals: initialLevel
+		| levelDuringTransaction |
 
+		levelDuringTransaction := System transactionLevel.
+		self extraterrestrials transact: [
+			self assert: System transactionLevel equals: levelDuringTransaction ].
+		self assert: System transactionLevel equals: levelDuringTransaction
+		].
+	self assert: System transactionLevel equals: baseLevel
 ]
 
 { #category : 'tests' }
 GemStoneRepositoryProviderTest >> testTransactionLevelWithManualAbort [
 
-	| initialLevel |
+	| baseLevel |
 
-	initialLevel := System transactionLevel.
-	self assert: initialLevel >= 0.
+	baseLevel := System transactionLevel.
 
 	self extraterrestrials transact: [
-		self assert: System transactionLevel equals: initialLevel + 1.
+		| levelDuringTransaction |
+
+		levelDuringTransaction := System transactionLevel.
 		self extraterrestrials transact: [
-			self assert: System transactionLevel equals: initialLevel + 2.
+			self assert: System transactionLevel equals: levelDuringTransaction.
 			System abortTransaction.
-			self assert: System transactionLevel equals: initialLevel + 1
+			self assert: System transactionLevel equals: levelDuringTransaction
 			].
-		self assert: System transactionLevel equals: initialLevel.
+		self assert: System transactionLevel equals: levelDuringTransaction
 		].
-	self assert: System transactionLevel equals: initialLevel
-
+	self assert: System transactionLevel equals: baseLevel
 ]
 
 { #category : 'tests' }
 GemStoneRepositoryProviderTest >> testTransactionLevelWithUnhandledException [
 
-	| initialLevel |
-
-	initialLevel := System transactionLevel.
-	self assert: initialLevel >= 0.
+	| baseLevel |
 
+	baseLevel := System transactionLevel.
 	[
+	| levelDuringTransaction |
+
 	self extraterrestrials transact: [
-		self assert: System transactionLevel equals: initialLevel + 1.
+		levelDuringTransaction := System transactionLevel.
 		self extraterrestrials transact: [
-			self assert: System transactionLevel equals: initialLevel + 2.
+			self assert: System transactionLevel equals: levelDuringTransaction.
 			1 / 0
 			]
 		]
@@ -395,8 +371,7 @@ GemStoneRepositoryProviderTest >> testTransactionLevelWithUnhandledException [
 		on: ZeroDivide
 		do: [ :ex | ex return ].
 
-	self assert: System transactionLevel equals: initialLevel
-
+	self assert: System transactionLevel equals: baseLevel
 ]
 
 { #category : 'utility' }
diff --git a/source/Sagan-GemStone/GemStoneRepository.class.st b/source/Sagan-GemStone/GemStoneRepository.class.st
index 4559fb6..47e8e69 100644
--- a/source/Sagan-GemStone/GemStoneRepository.class.st
+++ b/source/Sagan-GemStone/GemStoneRepository.class.st
@@ -65,19 +65,23 @@ GemStoneRepository >> findAllMatching: aCriteriaOrBlock sortedBy: aSortFunction
 { #category : 'configuring' }
 GemStoneRepository >> indexByEquality: aPath typed: aType [
 
-	GsIndexSpec new
-		equalityIndex: ( 'each.<1s>' expandMacrosWith: aPath )
-		lastElementClass: aType
-		options: self saganGemStoneIndexOptions;
-		createIndexesOn: contents
+	self transact: [
+		GsIndexSpec new
+			equalityIndex: ( 'each.<1s>' expandMacrosWith: aPath )
+			lastElementClass: aType
+			options: self saganGemStoneIndexOptions;
+			createIndexesOn: contents
+		]
 ]
 
 { #category : 'configuring' }
 GemStoneRepository >> indexByIdentity: aPath [
 
-	GsIndexSpec new
-		identityIndex: ( 'each.<1s>' expandMacrosWith: aPath ) options: self saganGemStoneIndexOptions;
-		createIndexesOn: contents
+	self transact: [
+		GsIndexSpec new
+			identityIndex: ( 'each.<1s>' expandMacrosWith: aPath ) options: self saganGemStoneIndexOptions;
+			createIndexesOn: contents
+		]
 ]
 
 { #category : 'initialization' }
@@ -96,18 +100,20 @@ GemStoneRepository >> matchingCriteriaBuilder [
 { #category : 'private - management' }
 GemStoneRepository >> purgeAfterCheckingInclusion: aDomainObject [
 
-	contents remove: aDomainObject ifAbsent: [
-		DataInconsistencyFound signal:
-			( '<1p> was expected to be found in the contents, but it was not.' expandMacrosWith:
-				  aDomainObject )
-		].
-	^ aDomainObject
+	^ self transact: [
+		  contents remove: aDomainObject ifAbsent: [
+			  DataInconsistencyFound signal:
+				  ( '<1p> was expected to be found in the contents, but it was not.' expandMacrosWith:
+					    aDomainObject )
+			  ].
+		  aDomainObject
+		  ]
 ]
 
 { #category : 'management' }
 GemStoneRepository >> purgeAllMatching: aCriteriaOrBlock [
 
-	contents := contents reject: ( self asMatchingCriteria: aCriteriaOrBlock )
+	self transact: [ contents := contents reject: ( self asMatchingCriteria: aCriteriaOrBlock ) ]
 ]
 
 { #category : 'private - accessing' }
@@ -120,8 +126,10 @@ GemStoneRepository >> saganGemStoneIndexOptions [
 { #category : 'private - management' }
 GemStoneRepository >> storeAfterCheckingConflicts: aDomainObject [
 
-	contents add: aDomainObject.
-	^ aDomainObject
+	^ self transact: [
+		  contents add: aDomainObject.
+		  aDomainObject
+		  ]
 ]
 
 { #category : 'management' }
@@ -133,7 +141,7 @@ GemStoneRepository >> transact: aBlock [
 { #category : 'management' }
 GemStoneRepository >> update: aMutableDomainObject executing: aBlock [
 
-	aBlock value: aMutableDomainObject
+	self transact: [ aBlock value: aMutableDomainObject ]
 ]
 
 { #category : 'private - management' }
diff --git a/source/Sagan-GemStone/GemStoneTransaction.class.st b/source/Sagan-GemStone/GemStoneTransaction.class.st
index ed97bd2..32b9b8f 100644
--- a/source/Sagan-GemStone/GemStoneTransaction.class.st
+++ b/source/Sagan-GemStone/GemStoneTransaction.class.st
@@ -11,15 +11,16 @@ Class {
 { #category : 'processing' }
 GemStoneTransaction >> transact: aBlock [
 
-	| result |
+	^ System inTransaction
+		  ifTrue: aBlock
+		  ifFalse: [
+			  | result |
 
-	System inTransaction
-		ifTrue: [ System beginNestedTransaction ]
-		ifFalse: [ System beginTransaction ].
-	[
-	result := aBlock value.
-	System commitTransaction
-	] ifCurtailed: [ result := System abortTransaction ].
-
-	^ result
+			  System beginTransaction.
+			  [
+			  result := aBlock value.
+			  System commitTransaction
+			  ] ifCurtailed: [ System abortTransaction ].
+			  result
+			  ]
 ]