diff --git a/src/LyXVC.cpp b/src/LyXVC.cpp
index c53996b698..168bf55782 100644
--- a/src/LyXVC.cpp
+++ b/src/LyXVC.cpp
@@ -313,7 +313,7 @@ bool LyXVC::undoLastEnabled() const
 	return vcs && vcs->undoLastEnabled();
 }
 
-bool LyXVC::prepareFileRevision(int rev, std::string & f)
+bool LyXVC::prepareFileRevision(string const & rev, std::string & f)
 {
 	return vcs && vcs->prepareFileRevision(rev, f);
 }
diff --git a/src/LyXVC.h b/src/LyXVC.h
index 0d9c826d5a..8cd2d89298 100644
--- a/src/LyXVC.h
+++ b/src/LyXVC.h
@@ -110,8 +110,9 @@ public:
 	 * Parameter rev can be either revision number or negative number
 	 * which is interpreted as how many revision back from the current
 	 * one do we want. rev=0 is reserved for the last (committed) revision.
+	 * We need rev to be string, since in various VCS revision is not integer.
 	 */
-	bool prepareFileRevision(int rev, std::string & f);
+	bool prepareFileRevision(std::string const & rev, std::string & f);
 	/// Does the current VC supports this operation?
 	bool prepareFileRevisionEnabled();
 
diff --git a/src/VCBackend.cpp b/src/VCBackend.cpp
index e90ddcd876..bf52e7006b 100644
--- a/src/VCBackend.cpp
+++ b/src/VCBackend.cpp
@@ -290,7 +290,7 @@ string RCS::revisionInfo(LyXVC::RevisionInfo const info)
 }
 
 
-bool RCS::prepareFileRevision(int, std::string &)
+bool RCS::prepareFileRevision(string const &, string &)
 {
 	return false;
 }
@@ -505,7 +505,7 @@ string CVS::revisionInfo(LyXVC::RevisionInfo const info)
 }
 
 
-bool CVS::prepareFileRevision(int, std::string &)
+bool CVS::prepareFileRevision(string const &, string &)
 {
 	return false;
 }
@@ -1006,8 +1006,12 @@ void SVN::getLog(FileName const & tmpf)
 }
 
 
-bool SVN::prepareFileRevision(int rev, string & f)
+bool SVN::prepareFileRevision(string const & revis, string & f)
 {
+	if (!isStrInt(revis))
+		return false;
+
+	int rev = convert<int>(revis);
 	if (rev <= 0)
 		if (!getFileRevisionInfo())
 			return false;
diff --git a/src/VCBackend.h b/src/VCBackend.h
index 6e8ef541de..a9bdb84a33 100644
--- a/src/VCBackend.h
+++ b/src/VCBackend.h
@@ -79,7 +79,7 @@ public:
 	/// Return revision info specified by the argument.
 	virtual std::string revisionInfo(LyXVC::RevisionInfo const info) = 0;
 
-	virtual bool prepareFileRevision(int rev, std::string & f) = 0;
+	virtual bool prepareFileRevision(std::string const & rev, std::string & f) = 0;
 
 	virtual bool prepareFileRevisionEnabled() = 0;
 
@@ -157,7 +157,7 @@ public:
 
 	virtual std::string revisionInfo(LyXVC::RevisionInfo const info);
 
-	virtual bool prepareFileRevision(int rev, std::string & f);
+	virtual bool prepareFileRevision(std::string const & rev, std::string & f);
 
 	virtual bool prepareFileRevisionEnabled();
 
@@ -218,7 +218,7 @@ public:
 
 	virtual std::string revisionInfo(LyXVC::RevisionInfo const info);
 
-	virtual bool prepareFileRevision(int rev, std::string & f);
+	virtual bool prepareFileRevision(std::string const & rev, std::string & f);
 
 	virtual bool prepareFileRevisionEnabled();
 
@@ -278,7 +278,7 @@ public:
 
 	virtual std::string revisionInfo(LyXVC::RevisionInfo const info);
 
-	virtual bool prepareFileRevision(int rev, std::string & f);
+	virtual bool prepareFileRevision(std::string const & rev, std::string & f);
 
 	virtual bool prepareFileRevisionEnabled();
 
diff --git a/src/frontends/qt4/GuiView.cpp b/src/frontends/qt4/GuiView.cpp
index e55ce92220..5cb73804d4 100644
--- a/src/frontends/qt4/GuiView.cpp
+++ b/src/frontends/qt4/GuiView.cpp
@@ -2579,22 +2579,20 @@ void GuiView::dispatchVC(FuncRequest const & cmd)
 		}
 
 	case LFUN_VC_COMPARE: {
-		if (!isStrInt(cmd.getArg(0)))
-			break;
-		int rev1 = convert<int>(cmd.getArg(0));
+
+		string rev1 = cmd.getArg(0);
 		string f1, f2;
 
 		// f1
 		if (!buffer->lyxvc().prepareFileRevision(rev1, f1))
 			break;
 
-		if (rev1 <= 0) {
+		if (isStrInt(rev1) && convert<int>(rev1) <= 0) {
 			f2 = buffer->absFileName();
 		} else {
-			string arg2 = cmd.getArg(1);
-			if (arg2.empty() || !isStrInt(arg2))
+			string rev2 = cmd.getArg(1);
+			if (rev2.empty() || !isStrInt(rev2))
 				break;
-			int rev2 = convert<int>(arg2);
 			// f2
 			if (!buffer->lyxvc().prepareFileRevision(rev2, f2))
 				break;