diff --git a/Apps/Common/SIMMultiPatchModelGen.h b/Apps/Common/SIMMultiPatchModelGen.h
index a6fa81b9..c1925234 100644
--- a/Apps/Common/SIMMultiPatchModelGen.h
+++ b/Apps/Common/SIMMultiPatchModelGen.h
@@ -31,13 +31,13 @@ public:
   //! \brief Constructor for standard problems.
   //! \param[in] n1 Dimension of the primary solution field
   //! \param[in] checkRHS If \e true, ensure the model is in a right-hand system
-  SIMMultiPatchModelGen(int n1, bool checkRHS = false) : Dim(n1,checkRHS) {}
+  explicit SIMMultiPatchModelGen(int n1, bool checkRHS = false) : Dim(n1,checkRHS) {}
 
   //! \brief Constructor for mixed problems.
   //! \param[in] unf Dimension of the primary solution field
   //! \param[in] checkRHS If \e true, ensure the model is in a right-hand system
-  SIMMultiPatchModelGen(const std::vector<unsigned char>& unf,
-                        bool checkRHS = false) : Dim(unf,checkRHS) {}
+  explicit SIMMultiPatchModelGen(const std::vector<unsigned char>& unf,
+                                 bool checkRHS = false) : Dim(unf,checkRHS) {}
 
   //! \brief Empty destructor.
   virtual ~SIMMultiPatchModelGen() {}
diff --git a/Apps/Common/SIMSolver.h b/Apps/Common/SIMSolver.h
index 99863803..93af4ed4 100644
--- a/Apps/Common/SIMSolver.h
+++ b/Apps/Common/SIMSolver.h
@@ -32,7 +32,7 @@ template<class T1> class SIMSolverStat : public SIMadmin
 {
 public:
   //! \brief The constructor initializes the reference to the actual solver.
-  SIMSolverStat(T1& s1, const char* head = nullptr) : SIMadmin(head), S1(s1)
+  explicit SIMSolverStat(T1& s1, const char* head = nullptr) : SIMadmin(head), S1(s1)
   {
     exporter = nullptr;
     startExpLevel = 0;
diff --git a/src/ASM/ASMs2DIB.h b/src/ASM/ASMs2DIB.h
index b9f3694c..4ce21256 100644
--- a/src/ASM/ASMs2DIB.h
+++ b/src/ASM/ASMs2DIB.h
@@ -37,7 +37,7 @@ class ASMs2DIB : public ASMs2D
     bool            alsoSW;  //!< If \e true, consider south/west neighbors too
   public:
     //! \brief The constructor initialises the reference to current patch.
-    Intersected(const ASMs2DIB& pch, bool all = false, bool sw = false)
+    explicit Intersected(const ASMs2DIB& pch, bool all = false, bool sw = false)
       : InterfaceChecker(pch), myAll(all), alsoSW(sw) {}
     //! \brief Empty destructor.
     virtual ~Intersected() {}
diff --git a/src/ASM/AlgEqSystem.h b/src/ASM/AlgEqSystem.h
index 7e97c33d..9da8da7b 100644
--- a/src/ASM/AlgEqSystem.h
+++ b/src/ASM/AlgEqSystem.h
@@ -26,7 +26,7 @@ class AlgEqSystem : public GlobalIntegral
 {
 public:
   //! \brief The constructor sets its reference to SAM and ProcessAdm objects.
-  AlgEqSystem(const SAM& s, const ProcessAdm* a = nullptr);
+  explicit AlgEqSystem(const SAM& s, const ProcessAdm* a = nullptr);
 
   //! \brief The destructor frees the dynamically allocated objects.
   virtual ~AlgEqSystem() { this->clear(); }
diff --git a/src/ASM/BlockElmMats.h b/src/ASM/BlockElmMats.h
index d3bd2659..bfbc214a 100644
--- a/src/ASM/BlockElmMats.h
+++ b/src/ASM/BlockElmMats.h
@@ -32,7 +32,7 @@ public:
   //! \brief The constructor initializes the block information arrays.
   //! \param[in] nBlk Number of matrix blocks (in each direction, row & column)
   //! \param[in] nb Number of bases (> 1 for mixed problems)
-  BlockElmMats(size_t nBlk, size_t nb = 1) : blockInfo(nBlk), basisInfo(nb) {}
+  explicit BlockElmMats(size_t nBlk, size_t nb = 1) : blockInfo(nBlk), basisInfo(nb) {}
   //! \brief Empty destructor.
   virtual ~BlockElmMats() {}
 
diff --git a/src/ASM/FiniteElement.h b/src/ASM/FiniteElement.h
index 8038972f..469b2505 100644
--- a/src/ASM/FiniteElement.h
+++ b/src/ASM/FiniteElement.h
@@ -98,7 +98,7 @@ class MxFiniteElement : public FiniteElement
 {
 public:
   //! \brief The constructor initializes the size of each basis.
-  MxFiniteElement(const std::vector<size_t>& n, size_t ip = 0);
+  explicit MxFiniteElement(const std::vector<size_t>& n, size_t ip = 0);
 
   //! \brief Empty destructor.
   virtual ~MxFiniteElement() {}
diff --git a/src/ASM/GlbNorm.h b/src/ASM/GlbNorm.h
index d5601f02..63e07e71 100644
--- a/src/ASM/GlbNorm.h
+++ b/src/ASM/GlbNorm.h
@@ -31,7 +31,7 @@ public:
   //! \brief The constructor initializes a reference to the global norm vector.
   //! \param[in] v Vector of global norm quantities
   //! \param[in] op Operation to be performed after accumulating element norms
-  GlbNorm(Vectors& v, ASM::FinalNormOp op = ASM::NONE);
+  explicit GlbNorm(Vectors& v, ASM::FinalNormOp op = ASM::NONE);
   //! \brief The destructor applies the operation \a myOp on \a myVals.
   virtual ~GlbNorm();
 
diff --git a/src/LinAlg/DenseMatrix.h b/src/LinAlg/DenseMatrix.h
index 3915c0e9..49cf5a77 100644
--- a/src/LinAlg/DenseMatrix.h
+++ b/src/LinAlg/DenseMatrix.h
@@ -31,9 +31,9 @@ public:
   //! \brief Copy constructor.
   DenseMatrix(const DenseMatrix& A);
   //! \brief Special constructor taking data from a one-dimensional array.
-  DenseMatrix(const RealArray& data, size_t nrows = 0);
+  explicit DenseMatrix(const RealArray& data, size_t nrows = 0);
   //! \brief Special constructor, type conversion from Matrix.
-  DenseMatrix(const Matrix& A, bool s = false);
+  explicit DenseMatrix(const Matrix& A, bool s = false);
   //! \brief The destructor frees the dynamically allocated arrays.
   virtual ~DenseMatrix() { if (ipiv) delete[] ipiv; }
 
diff --git a/src/LinAlg/SparseMatrix.h b/src/LinAlg/SparseMatrix.h
index 163e689b..373485e3 100644
--- a/src/LinAlg/SparseMatrix.h
+++ b/src/LinAlg/SparseMatrix.h
@@ -44,7 +44,7 @@ public:
   //! \brief Default constructor creating an empty matrix.
   SparseMatrix(SparseSolver eqSolver = NONE, int nt = 1);
   //! \brief Constructor creating a \f$m \times n\f$ matrix.
-  SparseMatrix(size_t m, size_t n = 0);
+  explicit SparseMatrix(size_t m, size_t n = 0);
   //! \brief Copy constructor.
   SparseMatrix(const SparseMatrix& B);
   //! \brief The destructor frees the dynamically allocated arrays.
diff --git a/src/LinAlg/matrixnd.h b/src/LinAlg/matrixnd.h
index 90e587dc..f90ad519 100644
--- a/src/LinAlg/matrixnd.h
+++ b/src/LinAlg/matrixnd.h
@@ -39,7 +39,7 @@ namespace utl
     //! \brief Copy constructor.
     matrix3d(const matrix3d<T>& mat) : matrixBase<T>(mat) {}
     //! \brief Constructor to read a matrix from a stream.
-    matrix3d(std::istream& is, std::streamsize max = 10)
+    explicit matrix3d(std::istream& is, std::streamsize max = 10)
     {
       // Read size
       size_t n0 = 0, n1 = 0, n2 = 0;
diff --git a/src/SIM/FunctionSum.h b/src/SIM/FunctionSum.h
index 416adf28..b9a82171 100644
--- a/src/SIM/FunctionSum.h
+++ b/src/SIM/FunctionSum.h
@@ -33,7 +33,7 @@ public:
   //! \brief The constructor specifies the first function to sum.
   //! \param[in] f Pointer to a function to sum
   //! \param[in] w Weighting factor. If negative, take max value instead.
-  FunctionSum(FunctionBase* f, double w = 1.0) { this->add(f,w); }
+  explicit FunctionSum(FunctionBase* f, double w = 1.0) { this->add(f,w); }
 
   //! \brief Empty destructor.
   virtual ~FunctionSum() {}
diff --git a/src/SIM/NonLinSIM.h b/src/SIM/NonLinSIM.h
index 97ffdf5c..56a02d75 100644
--- a/src/SIM/NonLinSIM.h
+++ b/src/SIM/NonLinSIM.h
@@ -39,7 +39,7 @@ public:
   //! \brief The constructor initializes default solution parameters.
   //! \param sim Pointer to the spline FE model
   //! \param[in] n Which type of iteration norm to use in convergence checks
-  NonLinSIM(SIMbase& sim, CNORM n = ENERGY);
+  explicit NonLinSIM(SIMbase& sim, CNORM n = ENERGY);
   //! \brief The destructor prints out the slow-converging nodes, if any.
   virtual ~NonLinSIM();
 
diff --git a/src/SIM/SIM1D.h b/src/SIM/SIM1D.h
index 75442fb2..c3b5f8b6 100644
--- a/src/SIM/SIM1D.h
+++ b/src/SIM/SIM1D.h
@@ -32,11 +32,11 @@ public:
   SIM1D(unsigned char n1 = 1, bool = false);
   //! \brief Constructor used for mixed problems.
   //! \param[in] unf Dimension of the primary solution fields
-  SIM1D(const CharVec& unf, bool = false);
+  explicit SIM1D(const CharVec& unf, bool = false);
   //! \brief Constructor that also initializes the integrand pointer.
   //! \param[in] itg Pointer to the integrand of the problem to solve
   //! \param[in] n Dimension of the primary solution field
-  SIM1D(IntegrandBase* itg, unsigned char n = 1);
+  explicit SIM1D(IntegrandBase* itg, unsigned char n = 1);
   //! \brief Empty destructor.
   virtual ~SIM1D() {}
 
diff --git a/src/SIM/SIM2D.h b/src/SIM/SIM2D.h
index 96886198..911dbc4a 100644
--- a/src/SIM/SIM2D.h
+++ b/src/SIM/SIM2D.h
@@ -36,12 +36,12 @@ public:
   //! \brief Constructor used for mixed problems.
   //! \param[in] unf Dimension of the primary solution fields
   //! \param[in] check If \e true, ensure the model is in a right-hand system
-  SIM2D(const CharVec& unf, bool check = false);
+  explicit SIM2D(const CharVec& unf, bool check = false);
   //! \brief Constructor that also initializes the integrand pointer.
   //! \param[in] itg Pointer to the integrand of the problem to solve
   //! \param[in] n Dimension of the primary solution field
   //! \param[in] check If \e true, ensure the model is in a right-hand system
-  SIM2D(IntegrandBase* itg, unsigned char n = 2, bool check = false);
+  explicit SIM2D(IntegrandBase* itg, unsigned char n = 2, bool check = false);
   //! \brief Empty destructor.
   virtual ~SIM2D() {}
 
diff --git a/src/SIM/SIM3D.h b/src/SIM/SIM3D.h
index d50e1211..9e7ea089 100644
--- a/src/SIM/SIM3D.h
+++ b/src/SIM/SIM3D.h
@@ -36,12 +36,12 @@ public:
   //! \brief Constructor used for mixed problems.
   //! \param[in] unf Dimension of the primary solution fields
   //! \param[in] check If \e true, ensure the model is in a right-hand system
-  SIM3D(const CharVec& unf, bool check = false);
+  explicit SIM3D(const CharVec& unf, bool check = false);
   //! \brief Constructor that also initializes the integrand pointer.
   //! \param[in] itg Pointer to the integrand of the problem to solve
   //! \param[in] n Dimension of the primary solution field
   //! \param[in] check If \e true, ensure the model is in a right-hand system
-  SIM3D(IntegrandBase* itg, unsigned char n = 3, bool check = false);
+  explicit SIM3D(IntegrandBase* itg, unsigned char n = 3, bool check = false);
   //! \brief Empty destructor.
   virtual ~SIM3D() {}
 
diff --git a/src/SIM/SIMmultiCpl.h b/src/SIM/SIMmultiCpl.h
index 03afca1f..87d18032 100644
--- a/src/SIM/SIMmultiCpl.h
+++ b/src/SIM/SIMmultiCpl.h
@@ -29,7 +29,7 @@ class SIMmultiCpl : public SIMadmin
 {
 public:
   //! \brief The constructor initializes the array of base %SIM objects.
-  SIMmultiCpl(const std::vector<SIMoutput*>& sims);
+  explicit SIMmultiCpl(const std::vector<SIMoutput*>& sims);
   //! \brief The destructor deletes the base %SIM objects.
   virtual ~SIMmultiCpl();
 
diff --git a/src/Utility/ExprFunctions.h b/src/Utility/ExprFunctions.h
index 53d336ac..5757e680 100644
--- a/src/Utility/ExprFunctions.h
+++ b/src/Utility/ExprFunctions.h
@@ -50,7 +50,7 @@ public:
   static int numError; //!< Error counter - set by the exception handler
 
   //! \brief The constructor parses the expression string.
-  EvalFunc(const char* function, const char* x = "x", Real eps = Real(1.0e-8));
+  explicit EvalFunc(const char* function, const char* x = "x", Real eps = Real(1.0e-8));
   //! \brief The destructor frees the dynamically allocated objects.
   virtual ~EvalFunc();
 
diff --git a/src/Utility/Functions.h b/src/Utility/Functions.h
index 2dc33937..585b4075 100644
--- a/src/Utility/Functions.h
+++ b/src/Utility/Functions.h
@@ -170,7 +170,7 @@ class StepFunc : public ScalarFunc
 
 public:
   //! \brief Constructor initializing the function parameters.
-  StepFunc(Real a, Real x = Real(0)) : amp(a), xmax(x) {}
+  explicit StepFunc(Real a, Real x = Real(0)) : amp(a), xmax(x) {}
 
   //! \brief Returns whether the function is identically zero or not.
   virtual bool isZero() const { return amp == Real(0); }
@@ -298,7 +298,7 @@ class LinearXFunc : public RealFunc
 
 public:
   //! \brief Constructor initializing the function parameters.
-  LinearXFunc(Real A, Real B = Real(0)) : a(A), b(B) {}
+  explicit LinearXFunc(Real A, Real B = Real(0)) : a(A), b(B) {}
 
   //! \brief Returns whether the function is identically zero or not.
   virtual bool isZero() const { return a == Real(0) && b == Real(0); }
@@ -323,7 +323,7 @@ class LinearYFunc : public RealFunc
 
 public:
   //! \brief Constructor initializing the function parameters.
-  LinearYFunc(Real A, Real B = Real(0)) : a(A), b(B) {}
+  explicit LinearYFunc(Real A, Real B = Real(0)) : a(A), b(B) {}
 
   //! \brief Returns whether the function is identically zero or not.
   virtual bool isZero() const { return a == Real(0) && b == Real(0); }
@@ -348,7 +348,7 @@ class LinearZFunc : public RealFunc
 
 public:
   //! \brief Constructor initializing the function parameters.
-  LinearZFunc(Real A, Real B = Real(0)) : a(A), b(B) {}
+  explicit LinearZFunc(Real A, Real B = Real(0)) : a(A), b(B) {}
 
   //! \brief Returns whether the function is identically zero or not.
   virtual bool isZero() const { return a == Real(0) && b == Real(0); }
@@ -497,7 +497,7 @@ class StepXFunc : public RealFunc
 
 public:
   //! \brief Constructor initializing the function parameters.
-  StepXFunc(Real v, Real X0 = Real(0), Real X1 = Real(1), char dir = 'X')
+  explicit StepXFunc(Real v, Real X0 = Real(0), Real X1 = Real(1), char dir = 'X')
     : fv(v), x0(X0), x1(X1), d(dir) {}
 
   //! \brief Returns whether the function is identically zero or not.
@@ -523,7 +523,7 @@ class StepXYFunc : public RealFunc
 
 public:
   //! \brief Constructor initializing the function parameters.
-  StepXYFunc(Real v,
+  explicit StepXYFunc(Real v,
              Real X1 = Real(1), Real Y1 = Real(1),
              Real X0 = Real(-1), Real Y0 = Real(-1))
     : fv(v), x0(X0), y0(Y0), x1(X1), y1(Y1) {}
diff --git a/src/Utility/LogStream.h b/src/Utility/LogStream.h
index 5c7a3d3b..98d5cfbf 100644
--- a/src/Utility/LogStream.h
+++ b/src/Utility/LogStream.h
@@ -32,7 +32,7 @@ public:
   //! \param out The output stream to wrap
   //! \param ppid The PID to print on
   //! \param mypid The PID of this process
-  LogStream(std::ostream& out, int ppid = 0, int mypid = 0);
+  explicit LogStream(std::ostream& out, int ppid = 0, int mypid = 0);
 
   //! \brief Nullifies the output stream.
   void setNull() { m_out = nullptr; }
diff --git a/src/Utility/Point.h b/src/Utility/Point.h
index f8edbdfe..983e6d4e 100644
--- a/src/Utility/Point.h
+++ b/src/Utility/Point.h
@@ -34,7 +34,7 @@ namespace utl
     Point() : Vec4(par) { par[0] = par[1] = par[2] = Real(0); }
 
     //! \brief Constructor creating a point at the specified location.
-    Point(const Vec3& X) : Vec4(X,Real(0),par)
+    explicit Point(const Vec3& X) : Vec4(X,Real(0),par)
     {
       par[0] = par[1] = par[2] = Real(0);
     }
@@ -54,7 +54,7 @@ namespace utl
     }
 
     //! \brief Constructor creating a point from the given \a std::vector.
-    Point(const std::vector<Real>& X) : Vec4(X,par)
+    explicit Point(const std::vector<Real>& X) : Vec4(X,par)
     {
       for (size_t i = 0; i < 3; i++)
         par[i] = 3+i < X.size() ? X[3+i] : 0.0;