diff --git a/modules/electromagnetics/include/bcs/AbsorbingBC.h b/modules/electromagnetics/include/bcs/AbsorbingBC.h
index 947a9b348cc1..26999743e9d3 100644
--- a/modules/electromagnetics/include/bcs/AbsorbingBC.h
+++ b/modules/electromagnetics/include/bcs/AbsorbingBC.h
@@ -23,9 +23,9 @@ class AbsorbingBC : public IntegratedBC
 
   MooseEnum _component;
 
-  Function & _func_real;
+  const Function & _func_real;
 
-  Function & _func_imag;
+  const Function & _func_imag;
 
   Real _coeff_real;
 
diff --git a/modules/electromagnetics/include/bcs/CoupledGradBC.h b/modules/electromagnetics/include/bcs/CoupledGradBC.h
index 69c58bb8116d..a3b6cc29f150 100644
--- a/modules/electromagnetics/include/bcs/CoupledGradBC.h
+++ b/modules/electromagnetics/include/bcs/CoupledGradBC.h
@@ -22,7 +22,7 @@ class CoupledGradBC : public IntegratedBC
 
   Real _coefficient;
 
-  Function & _func;
+  const Function & _func;
 
   const VariableGradient & _coupled_grad;
 };
diff --git a/modules/electromagnetics/include/bcs/PortBC.h b/modules/electromagnetics/include/bcs/PortBC.h
index f4d40a06a3ed..cefbb38e7cc5 100644
--- a/modules/electromagnetics/include/bcs/PortBC.h
+++ b/modules/electromagnetics/include/bcs/PortBC.h
@@ -23,13 +23,13 @@ class PortBC : public IntegratedBC
 
   MooseEnum _component;
 
-  Function & _func_real;
+  const Function & _func_real;
 
-  Function & _func_imag;
+  const Function & _func_imag;
 
-  Function & _profile_func_real;
+  const Function & _profile_func_real;
 
-  Function & _profile_func_imag;
+  const Function & _profile_func_imag;
 
   Real _coeff_real;
 
diff --git a/modules/electromagnetics/include/bcs/ReflectionBC.h b/modules/electromagnetics/include/bcs/ReflectionBC.h
index d874ffcb1c3b..63422cf65b84 100644
--- a/modules/electromagnetics/include/bcs/ReflectionBC.h
+++ b/modules/electromagnetics/include/bcs/ReflectionBC.h
@@ -23,9 +23,9 @@ class ReflectionBC : public IntegratedBC
 
   MooseEnum _component;
 
-  Function & _func_real;
+  const Function & _func_real;
 
-  Function & _func_imag;
+  const Function & _func_imag;
 
   Real _coeff_real;
 
diff --git a/modules/electromagnetics/include/bcs/VectorCurlPenaltyDirichletBC.h b/modules/electromagnetics/include/bcs/VectorCurlPenaltyDirichletBC.h
index 447fac2c0d9a..4d9d5ba1642b 100644
--- a/modules/electromagnetics/include/bcs/VectorCurlPenaltyDirichletBC.h
+++ b/modules/electromagnetics/include/bcs/VectorCurlPenaltyDirichletBC.h
@@ -20,9 +20,9 @@ class VectorCurlPenaltyDirichletBC : public VectorIntegratedBC
   virtual Real computeQpResidual();
   virtual Real computeQpJacobian();
   Real _penalty;
-  Function & _exact_x;
-  Function & _exact_y;
-  Function & _exact_z;
+  const Function & _exact_x;
+  const Function & _exact_y;
+  const Function & _exact_z;
 };
 
 #endif // VECTORCURLPENALTYDIRICHLETBC_H
diff --git a/modules/electromagnetics/include/bcs/VectorPortBC.h b/modules/electromagnetics/include/bcs/VectorPortBC.h
index 9ce5d8eabc37..f45edc654555 100644
--- a/modules/electromagnetics/include/bcs/VectorPortBC.h
+++ b/modules/electromagnetics/include/bcs/VectorPortBC.h
@@ -23,15 +23,15 @@ class VectorPortBC : public VectorIntegratedBC
   virtual Real computeQpJacobian() override;
   virtual Real computeQpOffDiagJacobian(unsigned int jvar) override;
 
-  Function & _beta;
+  const Function & _beta;
 
   MooseEnum _component;
 
   const VectorVariableValue & _coupled_val;
   unsigned int _coupled_var_num;
 
-  Function & _inc_real;
-  Function & _inc_imag;
+  const Function & _inc_real;
+  const Function & _inc_imag;
 
   std::complex<double> _jay;
 };
diff --git a/modules/electromagnetics/include/functions/HelmholtzTestFunc.h b/modules/electromagnetics/include/functions/HelmholtzTestFunc.h
index b6b721b7a9fa..3c89f44d0011 100644
--- a/modules/electromagnetics/include/functions/HelmholtzTestFunc.h
+++ b/modules/electromagnetics/include/functions/HelmholtzTestFunc.h
@@ -22,8 +22,8 @@ class HelmholtzTestFunc : public Function, public FunctionInterface
 protected:
   Real _L;
 
-  Function & _a;
-  Function & _b;
+  const Function & _a;
+  const Function & _b;
 
   Real _d;
   Real _h;
diff --git a/modules/electromagnetics/include/functions/JinSlabCoeffFunc.h b/modules/electromagnetics/include/functions/JinSlabCoeffFunc.h
index af8f0589b246..02c013afb4c5 100644
--- a/modules/electromagnetics/include/functions/JinSlabCoeffFunc.h
+++ b/modules/electromagnetics/include/functions/JinSlabCoeffFunc.h
@@ -20,8 +20,8 @@ class JinSlabCoeffFunc : public Function, public FunctionInterface
   virtual Real value(Real t, const Point & p) override;
 
 protected:
-  Function & _epsR_real;
-  Function & _epsR_imag;
+  const Function & _epsR_real;
+  const Function & _epsR_imag;
 
   Real _muR_real;
   Real _muR_imag;
diff --git a/modules/electromagnetics/include/functions/OneDFieldCoeff.h b/modules/electromagnetics/include/functions/OneDFieldCoeff.h
index 7464a9e4b5a6..928add5aa405 100644
--- a/modules/electromagnetics/include/functions/OneDFieldCoeff.h
+++ b/modules/electromagnetics/include/functions/OneDFieldCoeff.h
@@ -19,9 +19,9 @@ class OneDFieldCoeff : public Function, public FunctionInterface
 private:
   Real _theta;
 
-  Function & _epsR;
+  const Function & _epsR;
 
-  Function & _InverseMuR;
+  const Function & _InverseMuR;
 };
 
 #endif // ONEDFIELDCOEFF_H
diff --git a/modules/electromagnetics/include/functions/RobinTestFunc.h b/modules/electromagnetics/include/functions/RobinTestFunc.h
index e5f5540115a8..b47dc9d2c8ee 100644
--- a/modules/electromagnetics/include/functions/RobinTestFunc.h
+++ b/modules/electromagnetics/include/functions/RobinTestFunc.h
@@ -34,7 +34,7 @@ class RobinTestFunc : public Function, public FunctionInterface
   Real _gL_real;
   Real _gL_imag;
 
-  Function & _func;
+  const Function & _func;
 
   MooseEnum _component;
 };
diff --git a/modules/electromagnetics/include/functions/WaveCoeff.h b/modules/electromagnetics/include/functions/WaveCoeff.h
index 4428325c98cb..4283647367bf 100644
--- a/modules/electromagnetics/include/functions/WaveCoeff.h
+++ b/modules/electromagnetics/include/functions/WaveCoeff.h
@@ -20,11 +20,11 @@ class WaveCoeff : public Function, public FunctionInterface
   virtual Real value(Real t, const Point & p) override;
 
 protected:
-  Function & _eps_r_real;
-  Function & _eps_r_imag;
+  const Function & _eps_r_real;
+  const Function & _eps_r_imag;
 
-  Function & _mu_r_real;
-  Function & _mu_r_imag;
+  const Function & _mu_r_real;
+  const Function & _mu_r_imag;
 
   Real _k;
 
diff --git a/modules/electromagnetics/include/kernels/CoeffField.h b/modules/electromagnetics/include/kernels/CoeffField.h
index 1f1b413b4bd8..03b76f50e65e 100644
--- a/modules/electromagnetics/include/kernels/CoeffField.h
+++ b/modules/electromagnetics/include/kernels/CoeffField.h
@@ -21,7 +21,7 @@ class CoeffField : public Reaction
 private:
   Real _coefficient;
 
-  Function & _func;
+  const Function & _func;
 };
 
 #endif /* COEFFFIELD_H */
diff --git a/modules/electromagnetics/include/kernels/CoupledCoeffField.h b/modules/electromagnetics/include/kernels/CoupledCoeffField.h
index adf58a2b59d9..920d76121819 100644
--- a/modules/electromagnetics/include/kernels/CoupledCoeffField.h
+++ b/modules/electromagnetics/include/kernels/CoupledCoeffField.h
@@ -21,7 +21,7 @@ class CoupledCoeffField : public Kernel
 private:
   Real _coefficient;
 
-  Function & _func;
+  const Function & _func;
 
   const VariableValue & _coupled_val;
 
diff --git a/modules/electromagnetics/include/kernels/CoupledFuncDiffusion.h b/modules/electromagnetics/include/kernels/CoupledFuncDiffusion.h
index 748f95335402..9c7f46b5af1a 100644
--- a/modules/electromagnetics/include/kernels/CoupledFuncDiffusion.h
+++ b/modules/electromagnetics/include/kernels/CoupledFuncDiffusion.h
@@ -19,7 +19,7 @@ class CoupledFuncDiffusion : public Kernel
 
 private:
 
-  Function & _func;
+  const Function & _func;
 
   Real _sign;
 
diff --git a/modules/electromagnetics/include/kernels/CoupledVectorCoeffField.h b/modules/electromagnetics/include/kernels/CoupledVectorCoeffField.h
index da9932264570..1a6376fd50fe 100644
--- a/modules/electromagnetics/include/kernels/CoupledVectorCoeffField.h
+++ b/modules/electromagnetics/include/kernels/CoupledVectorCoeffField.h
@@ -19,7 +19,7 @@ class CoupledVectorCoeffField : public VectorKernel
 
   Real _coefficient;
 
-  Function & _func;
+  const Function & _func;
 
   const VectorVariableValue & _coupled_val;
 };
diff --git a/modules/electromagnetics/include/kernels/FuncDiffusion.h b/modules/electromagnetics/include/kernels/FuncDiffusion.h
index 6e916fb56494..82e5268400e6 100644
--- a/modules/electromagnetics/include/kernels/FuncDiffusion.h
+++ b/modules/electromagnetics/include/kernels/FuncDiffusion.h
@@ -19,7 +19,7 @@ class FuncDiffusion : public Diffusion
 
 private:
 
-  Function & _func;
+  const Function & _func;
 };
 
 #endif // FUNCDIFFUSION_H
diff --git a/modules/electromagnetics/include/kernels/VectorCoeffField.h b/modules/electromagnetics/include/kernels/VectorCoeffField.h
index 3d31c0af9b16..a380f406dfb3 100644
--- a/modules/electromagnetics/include/kernels/VectorCoeffField.h
+++ b/modules/electromagnetics/include/kernels/VectorCoeffField.h
@@ -19,7 +19,7 @@ class VectorCoeffField : public VectorKernel
 
   Real _coefficient;
 
-  Function & _func;
+  const Function & _func;
 };
 
 #endif // VECTORCOEFFFIELD_H
diff --git a/modules/electromagnetics/include/kernels/VectorCurrentSource.h b/modules/electromagnetics/include/kernels/VectorCurrentSource.h
index 4e29bbd1aae0..f4615076791a 100644
--- a/modules/electromagnetics/include/kernels/VectorCurrentSource.h
+++ b/modules/electromagnetics/include/kernels/VectorCurrentSource.h
@@ -17,10 +17,10 @@ class VectorCurrentSource : public VectorKernel
   virtual Real computeQpResidual() override;
   virtual Real computeQpJacobian() override;
 
-  Function & _func;
+  const Function & _func;
 
-  Function & _source_real;
-  Function & _source_imag;
+  const Function & _source_real;
+  const Function & _source_imag;
 
   MooseEnum _component;
 };
diff --git a/modules/electromagnetics/test/include/functions/MMSTestFunc.h b/modules/electromagnetics/test/include/functions/MMSTestFunc.h
index 8253d5c76989..52764f935241 100644
--- a/modules/electromagnetics/test/include/functions/MMSTestFunc.h
+++ b/modules/electromagnetics/test/include/functions/MMSTestFunc.h
@@ -22,8 +22,8 @@ class MMSTestFunc : public Function, public FunctionInterface
 protected:
   Real _L;
 
-  Function & _a;
-  Function & _b;
+  const Function & _a;
+  const Function & _b;
 
   Real _d;
   Real _h;