diff --git a/src/scgenerator/__init__.py b/src/scgenerator/__init__.py
index 4b9812e..5ad3505 100644
--- a/src/scgenerator/__init__.py
+++ b/src/scgenerator/__init__.py
@@ -7,4 +7,4 @@ from scgenerator.parameter import Parameters
 from scgenerator.physics import fiber, materials, plasma, pulse, units
 from scgenerator.physics.units import PlotRange
 from scgenerator.solver import SimulationResult, integrate, solve43
-from scgenerator.spectra import Propagation, Spectrum
+from scgenerator.spectra import Spectrum, propagation
diff --git a/src/scgenerator/parameter.py b/src/scgenerator/parameter.py
index 89f3952..e49fcda 100644
--- a/src/scgenerator/parameter.py
+++ b/src/scgenerator/parameter.py
@@ -553,7 +553,7 @@ class Parameters:
         else:
             return first
 
-    def compile(self, exhaustive=False, strict: bool = True) -> Parameters:
+    def compile(self, *, exhaustive=False, strict: bool = True) -> Parameters:
         """
         Computes missing parameters and returns them in a frozen `Parameters` instance