diff --git a/modoboa_installer/compatibility_matrix.py b/modoboa_installer/compatibility_matrix.py
new file mode 100644
index 0000000..8da21a4
--- /dev/null
+++ b/modoboa_installer/compatibility_matrix.py
@@ -0,0 +1,8 @@
+"""Modoboa compatibility matrix."""
+
+COMPATIBILITY_MATRIX = {
+}
+
+EXTENSIONS_AVAILABILITY = {
+    "modoboa-contacts": "1.7.4",
+}
diff --git a/modoboa_installer/scripts/modoboa.py b/modoboa_installer/scripts/modoboa.py
index a7b7512..6c8361e 100644
--- a/modoboa_installer/scripts/modoboa.py
+++ b/modoboa_installer/scripts/modoboa.py
@@ -7,6 +7,7 @@ import shutil
 import stat
 import sys
 
+from .. import compatibility_matrix
 from .. import package
 from .. import python
 from .. import utils
@@ -50,10 +51,36 @@ class Modoboa(base.Installer):
             else:
                 self.extensions.remove("modoboa-amavis")
 
+    def is_extension_ok_for_version(self, extension, version):
+        """Check if extension can be installed with this modo version."""
+        if extension not in compatibility_matrix.EXTENSIONS_AVAILABILITY:
+            return True
+        version = utils.convert_version_to_int(version)
+        min_version = compatibility_matrix.EXTENSIONS_AVAILABILITY[extension]
+        min_version = utils.convert_version_to_int(min_version)
+        return version >= min_version
+
     def _setup_venv(self):
         """Prepare a dedicated virtualenv."""
         python.setup_virtualenv(self.venv_path, sudo_user=self.user)
-        packages = ["modoboa", "rrdtool"]
+        packages = ["rrdtool"]
+        version = self.config.get("modoboa", "version")
+        if version == "latest":
+            packages += ["modoboa"] + self.extensions
+        else:
+            matrix = compatibility_matrix.COMPATIBILITY_MATRIX[version]
+            packages.append("modoboa=={}".format(version))
+            for extension in list(self.extensions):
+                if not self.is_extension_ok_for_version(extension, version):
+                    self.extensions.remove(extension)
+                    continue
+                if extension in matrix:
+                    req_version = matrix[extension]
+                    req_version = req_version.replace("<", "\<")
+                    req_version = req_version.replace(">", "\>")
+                    packages.append("{}{}".format(extension, req_version))
+                else:
+                    packages.append(extension)
         if self.dbengine == "postgres":
             packages.append("psycopg2")
         else:
@@ -91,6 +118,7 @@ class Modoboa(base.Installer):
             "--timezone", self.config.get("modoboa", "timezone"),
             "--domain", self.config.get("general", "hostname"),
             "--extensions", " ".join(self.extensions),
+            "--dont-install-extensions",
             "--dburl", "'default:{0}://{1}:{2}@{3}/{1}'".format(
                 self.config.get("database", "engine"), self.dbname,
                 self.dbpasswd, self.dbhost)
diff --git a/modoboa_installer/utils.py b/modoboa_installer/utils.py
index 68e43f4..e4baee8 100644
--- a/modoboa_installer/utils.py
+++ b/modoboa_installer/utils.py
@@ -171,6 +171,8 @@ def has_colours(stream):
     except:
         # guess false in case of error
         return False
+
+
 has_colours = has_colours(sys.stdout)
 
 
@@ -179,3 +181,30 @@ def printcolor(message, color):
     if has_colours:
         message = "\x1b[1;{}m{}\x1b[0m".format(30 + color, message)
     print(message)
+
+
+def convert_version_to_int(version):
+    """Convert a version string to an integer."""
+    number_bits = (8, 8, 16)
+
+    numbers = [int(number_string) for number_string in version.split(".")]
+    if len(numbers) > len(number_bits):
+        raise NotImplementedError(
+            "Versions with more than {0} decimal places are not supported"
+            .format(len(number_bits) - 1)
+        )
+    # add 0s for missing numbers
+    numbers.extend([0] * (len(number_bits) - len(numbers)))
+    # convert to single int and return
+    number = 0
+    total_bits = 0
+    for num, bits in reversed(list(zip(numbers, number_bits))):
+        max_num = (bits + 1) - 1
+        if num >= 1 << max_num:
+            raise ValueError(
+                "Number {0} cannot be stored with only {1} bits. Max is {2}"
+                .format(num, bits, max_num)
+            )
+        number += num << total_bits
+        total_bits += bits
+    return number
diff --git a/run.py b/run.py
index e0f600b..385829e 100755
--- a/run.py
+++ b/run.py
@@ -8,10 +8,11 @@ try:
 except ImportError:
     import ConfigParser as configparser
 
-from modoboa_installer import scripts
-from modoboa_installer import utils
+from modoboa_installer import compatibility_matrix
 from modoboa_installer import package
+from modoboa_installer import scripts
 from modoboa_installer import ssl
+from modoboa_installer import utils
 
 
 def main():
@@ -23,6 +24,10 @@ def main():
                         help="Force installation")
     parser.add_argument("--configfile", default="installer.cfg",
                         help="Configuration file to use")
+    parser.add_argument(
+        "--version", default="latest",
+        choices=["latest"] + compatibility_matrix.COMPATIBILITY_MATRIX.keys(),
+        help="Modoboa version to install")
     parser.add_argument(
         "--stop-after-configfile-check", action="store_true", default=False,
         help="Check configuration, generate it if needed and exit")
@@ -42,6 +47,7 @@ def main():
     if not config.has_section("general"):
         config.add_section("general")
     config.set("general", "domain", args.domain)
+    config.set("modoboa", "version", args.version)
     utils.printcolor(
         "Your mail server will be installed with the following components:",
         utils.BLUE)
@@ -80,5 +86,6 @@ def main():
         .format(config.get("general", "hostname")),
         utils.GREEN)
 
+
 if __name__ == "__main__":
     main()