diff --git a/scopesim/effects/metis_wcu/metis_wcu.py b/scopesim/effects/metis_wcu/metis_wcu.py
index 04e589af9..7f8659bc8 100644
--- a/scopesim/effects/metis_wcu/metis_wcu.py
+++ b/scopesim/effects/metis_wcu/metis_wcu.py
@@ -6,6 +6,7 @@
 """
 
 from typing import ClassVar
+from collections.abc import Iterable
 
 import numpy as np
 from astropy.table import Table
@@ -200,6 +201,46 @@ def set_lamp(self, lamp="bb"):
         self.compute_lamp_emission()
         self.compute_fp_emission()
 
+    def tune_laser(self, wavelength, force=False):
+        """Set the wavelength(s) of the tunable laser
+
+        Parameters
+        ==========
+        wavelength : float, list, array [um]
+            The wavelength(s) at which the laser emits
+        force: boolean [True] <- currently not used
+            If True bypass the validation for the lasers available
+            wavelength range.
+        """
+        if not isinstance(wavelength, Iterable):
+            wavelength = [wavelength]
+        if not force:
+            wavelength = self._validate_tunable(wavelength)
+
+        # if nothing's there use a dummy value outside any range
+        # to prevent division by zero
+        if len(wavelength) == 0:
+            wavelength = [0.001]
+
+        self.meta["laser_t_wave"] = wavelength
+        self.compute_lamp_emission()
+        self.compute_fp_emission()
+
+    def _validate_tunable(self, wave):
+        """Validate wave against a wavelength range
+
+        This is currently not used as there is no reliable
+        information on the tuning range of the QCL.
+        """
+        lam_min, lam_max = self.meta["laser_t_wave_limits"]
+
+        accept = [w for w in wave if (w >= lam_min) & (w <= lam_max)]
+        n_rejected = len(wave) - len(accept)
+        if n_rejected > 0:
+            logger.warning("Removed %d wavelengths outside allowed range (%.2f, %.2f) um",
+                           n_rejected, lam_min, lam_max)
+        return accept
+
     def get_wavelength(self):
         """Try to set the appropriate wavelength vector for mode and filter."""
         # Need to provide for wcu_lms_extended
@@ -423,24 +464,26 @@ def _laser_intensity(self):
         The function computes all three lasers at once. This is possible because
         the lines are so far apart that there is no band that sees them both.
         """
-        print("Computing laser intensity")
+        logger.info("Computing laser intensity")
         lam = self.wavelength
         dlam = lam[1] - lam[0]
 
         mult_is = self.is_multiplication(lam)
 
         # Laser 1 (L band)  # TODO move to yaml
-        lamc_l = 3.39 * u.um
-        power_l = 5e-3 * u.W / (c.c * c.h / lamc_l) * u.ph
+        lamc_l = self.meta["laser_l_wave"] * u.um
+        power_l = self.meta["laser_l_power"] * u.W / (c.c * c.h / lamc_l) * u.ph
 
         # Laser 2 (tunable), power divided among multiple lines
-        lam_t = seq(4.68, 4.78, 0.01) * u.um
+        if not isinstance(self.meta['laser_t_wave'], Iterable):
+            self.meta['laser_t_wave'] = [self.meta['laser_t_wave']]
+        lam_t = self.meta["laser_t_wave"] * u.um
         nline = len(lam_t)
-        power_t = 70e-3 * u.W / (c.c * c.h / lam) * u.ph / nline
+        power_t = self.meta["laser_t_power"] * u.W / (c.c * c.h / lam) * u.ph / nline
 
         # Laser 3 (M band)
-        lamc_m = 5.26 * u.um
-        power_m = 20e-3 * u.W / (c.c * c.h / lamc_m) * u.ph
+        lamc_m = self.meta["laser_m_wave"] * u.um
+        power_m = self.meta["laser_m_power"] * u.W / (c.c * c.h / lamc_m) * u.ph
 
         # Apply fibre transmission
         power_l *= self.fibre_trans
diff --git a/scopesim/tests/tests_effects/test_MetisWCU.py b/scopesim/tests/tests_effects/test_MetisWCU.py
index 5261e4065..8c8f63d47 100644
--- a/scopesim/tests/tests_effects/test_MetisWCU.py
+++ b/scopesim/tests/tests_effects/test_MetisWCU.py
@@ -40,6 +40,13 @@ def fixture_bbsource():
                      bb_temp=1000*u.K,
                      is_temp=300*u.K,
                      wcu_temp=300*u.K,
+                     laser_l_wave=3.39,    # [um]
+                     laser_l_power=5e-3,   # [W]
+                     laser_t_wave=[4.70],  # [um], array
+                     laser_t_wave_limits=[1., 30.],  # [um]
+                     laser_t_power=70e-3,  # [W]
+                     laser_m_wave=5.26,    # [um]
+                     laser_m_power=20e-3,  # [W]
                      bb_aperture=1.,
                      bb_to_is=None,
                      rho_tube=0.95,
@@ -211,7 +218,18 @@ def test_laser_brighter_with_fibre_transmission(self, bbsource):
         bbsource.set_lamp("laser")
         intens_2 = np.sum(bbsource.intens_lamp)
 
-        assert intens_2 / intens_1 == ft_2 / ft_1
+        npt.assert_allclose(intens_2 / intens_1, ft_2 / ft_1)
+
+
+    def test_can_tune_laser(self, bbsource):
+        bbsource.set_lamp("laser")
+        assert bbsource.meta["laser_t_wave"] == [4.70]
+        bbsource.tune_laser(4.72)
+        assert bbsource.meta["laser_t_wave"] == [4.72]
+        bbsource.tune_laser(np.linspace(4.68, 4.72, 10))
+        assert len(bbsource.meta["laser_t_wave"]) == 10
+        bbsource.tune_laser([])
+        assert bbsource.meta["laser_t_wave"] == [0.001]
 
 
 @pytest.fixture(name="fpmask", scope="function")