diff --git a/src/support/Systemcall.cpp b/src/support/Systemcall.cpp
index f8db8b0b68..bc7790adb1 100644
--- a/src/support/Systemcall.cpp
+++ b/src/support/Systemcall.cpp
@@ -100,8 +100,13 @@ ProgressInterface* ProgressInterface::instance()
 int Systemcall::startscript(Starttype how, string const & what,
 			    std::string const & path, bool /*process_events*/)
 {
-	string command =
-		to_filesystem8bit(from_utf8(latexEnvCmdPrefix(path))) + what;
+	string const python_call = "python -tt";
+	string command = to_filesystem8bit(from_utf8(latexEnvCmdPrefix(path)));
+
+	if (prefixIs(what, python_call))
+		command += os::python() + what.substr(python_call.length());
+	else
+		command += what;
 
 	if (how == DontWait) {
 		switch (os::shell()) {
@@ -162,9 +167,16 @@ string const parsecmd(string const & inputcmd, string & outfile)
 	bool in_single_quote = false;
 	bool in_double_quote = false;
 	bool escaped = false;
+	string const python_call = "python -tt";
 	string cmd;
+	int start = 0;
 
-	for (size_t i = 0; i < inputcmd.length(); ++i) {
+	if (prefixIs(inputcmd, python_call)) {
+		cmd = os::python();
+		start = python_call.length();
+	}
+
+	for (size_t i = start; i < inputcmd.length(); ++i) {
 		char c = inputcmd[i];
 		if (c == '\'') {
 			if (in_double_quote || escaped) {
diff --git a/src/support/os.cpp b/src/support/os.cpp
index 820f4e9a66..a18637c772 100644
--- a/src/support/os.cpp
+++ b/src/support/os.cpp
@@ -4,13 +4,19 @@
  * Licence details can be found in the file COPYING.
  *
  * \author Ruurd A. Reitsma
+ * \author Enrico Forestieri
  *
  * Full author contact details are available in file CREDITS.
  */
 
 #include <config.h>
 
-#if defined(__CYGWIN__) || defined(__CYGWIN32__)
+#include "filetools.h"
+#include "qstring_helpers.h"
+
+#include <QDir>
+
+#if defined(__CYGWIN__)
 #include "support/os_cygwin.cpp"
 #elif defined(_WIN32)
 #include "support/os_win32.cpp"
@@ -31,11 +37,57 @@ namespace lyx {
 namespace support {
 namespace os {
 
+static string const python2(string const & binary, bool verbose = false)
+{
+	if (verbose)
+		lyxerr << "Examining " << binary << "\n";
+
+	// Check whether this is a python 2 binary.
+	cmd_ret const out = runCommand(binary + " -V 2>&1");
+	if (out.first < 0 || !prefixIs(out.second, "Python 2"))
+		return string();
+
+	if (verbose)
+		lyxerr << "Found " << out.second << "\n";
+	return binary;
+}
+
+
 string const python()
 {
-	// Use the -tt switch so that mixed tab/whitespace indentation is
-	// an error
-	static string const command("python -tt");
+	// Check whether the first python in PATH is the right one.
+	static string command = python2("python -tt");
+
+	if (command.empty()) {
+		// It was not, so check whether we can find it elsewhere in
+		// PATH, maybe with some suffix appended.
+		vector<string> const path = getEnvPath("PATH");
+		vector<string>::const_iterator it = path.begin();
+		vector<string>::const_iterator const end = path.end();
+		lyxerr << "Looking for python v2.x ...\n";
+		for (; it != end; ++it) {
+			QString const dir = toqstr(*it);
+			string const localdir = dir.toLocal8Bit().constData();
+			QDir qdir(dir);
+			qdir.setFilter(QDir::Files | QDir::Executable);
+			QStringList list = qdir.entryList(QStringList("python*"));
+			for (int i = 0; i < list.size() && command.empty(); ++i) {
+				string const binary = addName(localdir,
+					list.at(i).toLocal8Bit().constData());
+				command = python2(binary, true);
+			}
+		}
+
+		// Default to "python" if no usable binary was found.
+		if (command.empty()) {
+			lyxerr << "Warning: No python v2.x binary found.\n";
+			command = "python";
+		}
+
+		// Add the -tt switch so that mixed tab/whitespace
+		// indentation is an error
+		command += " -tt";
+	}
 	return command;
 }