diff --git a/src/VCBackend.cpp b/src/VCBackend.cpp
index 599e331364..bb963f1f15 100644
--- a/src/VCBackend.cpp
+++ b/src/VCBackend.cpp
@@ -2213,15 +2213,54 @@ void GIT::getLog(FileName const & tmpf)
 }
 
 
-bool GIT::prepareFileRevision(string const & /*revis*/, string & /*f*/)
+//at this moment we don't accept revision SHA, but just number of revision steps back
+//GUI and infrastucture needs to be changed first
+bool GIT::prepareFileRevision(string const & revis, string & f)
 {
-	return false;
+	// anything positive means we got hash, not "0" or minus revision
+	int rev = 1;
+
+	// hash is rarely number and should be long
+	if (isStrInt(revis) && revis.length()<20)
+		rev = convert<int>(revis);
+
+	// revision and filename
+	string pointer;
+
+	// go back for "minus" revisions
+	if (rev <= 0)
+		pointer = "HEAD~" + convert<string>(-rev);
+	// normal hash
+	else
+		pointer = revis;
+
+	pointer += ":";
+
+	if (rev <= 0)
+		if (!getFileRevisionInfo())
+			return false;
+
+	FileName tmpf = FileName::tempName("lyxvcrev_" + revis + "_");
+	if (tmpf.empty()) {
+		LYXERR(Debug::LYXVC, "Could not generate logfile " << tmpf);
+		return false;
+	}
+
+	doVCCommand("git show " + pointer + "./"
+	              + quoteName(onlyFileName(owner_->absFileName()))
+		      + " > " + quoteName(tmpf.toFilesystemEncoding()),
+		FileName(owner_->filePath()));
+	if (tmpf.isFileEmpty())
+		return false;
+
+	f = tmpf.absFileName();
+	return true;
 }
 
 
 bool GIT::prepareFileRevisionEnabled()
 {
-	return false;
+	return true;
 }
 
 
diff --git a/src/frontends/qt4/GuiCompareHistory.cpp b/src/frontends/qt4/GuiCompareHistory.cpp
index 711cd51dcb..d176a387c4 100644
--- a/src/frontends/qt4/GuiCompareHistory.cpp
+++ b/src/frontends/qt4/GuiCompareHistory.cpp
@@ -10,6 +10,7 @@
 
 #include <config.h>
 #include <support/debug.h>
+#include <limits>
 
 #include "GuiCompareHistory.h"
 
@@ -51,11 +52,22 @@ bool GuiCompareHistory::initialiseParams(std::string const &)
 	int rev=0;
 
 	string tmp;
-	// RCS case
-	if (!isStrInt(revstring))
-		revstring = rsplit(revstring, tmp , '.' );
-	if (isStrInt(revstring))
-		rev = convert<int>(revstring);
+	bool enableBetween = true;
+	// GIT case, hash is long
+	if (revstring.length() > 20) {
+		enableBetween = false;
+		rev = numeric_limits<int>::max();
+	} else {
+		// RCS case
+		if (!isStrInt(revstring))
+			revstring = rsplit(revstring, tmp , '.' );
+		// both SVN & RCS cases
+		if (isStrInt(revstring))
+			rev = convert<int>(revstring);
+	}
+
+	// later we can provide comparison between two hashes
+	betweenrevRB->setEnabled(enableBetween);
 
 	okPB->setEnabled(rev);
 	rev1SB->setMaximum(rev);