diff --git a/src/Microdown-Rules/MicCodeIndentationChecker.class.st b/src/Microdown-Rules/MicCodeIndentationChecker.class.st
new file mode 100644
index 00000000..8e8ce4f0
--- /dev/null
+++ b/src/Microdown-Rules/MicCodeIndentationChecker.class.st
@@ -0,0 +1,30 @@
+"
+I check that code blocks use tabs for indentation instead of spaces.
+A line that starts with a space character is considered incorrectly indented.
+"
+Class {
+	#name : 'MicCodeIndentationChecker',
+	#superclass : 'MicChecker',
+	#category : 'Microdown-Rules-CodeIndetation',
+	#package : 'Microdown-Rules',
+	#tag : 'CodeIndetation'
+}
+
+{ #category : 'visiting' }
+MicCodeIndentationChecker >> visitCode: aMicCode [
+	| lines |
+	lines := aMicCode body lines.
+	lines do: [ :line |
+		line isEmpty ifFalse: [ 
+			"verify if the line begin with space"
+			(line first = Character space) ifTrue: [ 
+					results add: (MicCodeIndentationResult new 
+						micElement: aMicCode;
+						inFile: aMicCode fromFile;
+						detail: line;
+						yourself
+					)
+				 ]
+			 ]
+		 ]
+]
diff --git a/src/Microdown-Rules/MicCodeIndentationCheckerTest.class.st b/src/Microdown-Rules/MicCodeIndentationCheckerTest.class.st
new file mode 100644
index 00000000..668f38fc
--- /dev/null
+++ b/src/Microdown-Rules/MicCodeIndentationCheckerTest.class.st
@@ -0,0 +1,53 @@
+Class {
+	#name : 'MicCodeIndentationCheckerTest',
+	#superclass : 'TestCase',
+	#instVars : [
+		'fileSystem',
+		'checker'
+	],
+	#category : 'Microdown-Rules-CodeIndetation',
+	#package : 'Microdown-Rules',
+	#tag : 'CodeIndetation'
+}
+
+{ #category : 'running' }
+MicCodeIndentationCheckerTest >> generateFilesystemExample [
+	| file |
+	"incorrect cases - space instead of tabs"
+	file := fileSystem workingDirectory / 'indentationWrong.md'.
+	file writeStreamDo: [ :stream |
+		stream nextPutAll: '```
+foo
+   self
+		`````'
+		 ].
+	"correct cases - tabs"
+	file := fileSystem workingDirectory / 'indentationCorrect.md'.
+	file writeStreamDo: [  :stream |
+		stream nextPutAll: '```
+foo
+	self
+		````' ].
+]
+
+{ #category : 'running' }
+MicCodeIndentationCheckerTest >> setUp [
+	super setUp.
+
+	fileSystem := FileSystem memory.
+	self generateFilesystemExample.
+	checker := MicCodeIndentationChecker new.
+]
+
+{ #category : 'tests' }
+MicCodeIndentationCheckerTest >> testIndentationCorrect [
+	checker checkProject: fileSystem / 'indentationCorrect.md'.
+	self assert: checker isOkay.
+]
+
+{ #category : 'tests' }
+MicCodeIndentationCheckerTest >> testIndentationWrongDetected [
+	checker checkProject: fileSystem / 'indentationWrong.md'.
+	self deny: checker isOkay.
+	self assert: checker results size equals: 1.
+]
diff --git a/src/Microdown-Rules/MicCodeIndentationResult.class.st b/src/Microdown-Rules/MicCodeIndentationResult.class.st
new file mode 100644
index 00000000..28d3ee17
--- /dev/null
+++ b/src/Microdown-Rules/MicCodeIndentationResult.class.st
@@ -0,0 +1,31 @@
+Class {
+	#name : 'MicCodeIndentationResult',
+	#superclass : 'MicAbstractResult',
+	#instVars : [
+		'detail'
+	],
+	#category : 'Microdown-Rules-CodeIndetation',
+	#package : 'Microdown-Rules',
+	#tag : 'CodeIndetation'
+}
+
+{ #category : 'accessing' }
+MicCodeIndentationResult >> detail [
+
+	^ detail
+]
+
+{ #category : 'accessing' }
+MicCodeIndentationResult >> detail: anObject [
+
+	detail := anObject
+]
+
+{ #category : 'accessing' }
+MicCodeIndentationResult >> explanation [ 
+	^ 'Text: "' , micElement body
+	, '" in file' , fileReference fullName
+	, ' contains a mistake: line ['
+	, detail 
+	, '] should use tabs instead of spaces for indentation.'
+]