diff --git a/avogadro/core/coordinateblockgenerator.cpp b/avogadro/core/coordinateblockgenerator.cpp
index 147fe519cc..ddf3c24314 100644
--- a/avogadro/core/coordinateblockgenerator.cpp
+++ b/avogadro/core/coordinateblockgenerator.cpp
@@ -64,8 +64,8 @@ std::string CoordinateBlockGenerator::generateCoordinateBlock()
   const Index numAtoms = m_molecule->atomCount();
   Atom atom;
   unsigned char atomicNumber;
-  const char* symbol;
-  const char* name;
+  const char* symbol = "\0";
+  const char* name = "\0";
   Vector3 pos3d;
   Vector3 fpos3d;
   const UnitCell* cell =
diff --git a/avogadro/core/dihedraliterator.cpp b/avogadro/core/dihedraliterator.cpp
index cc93c04b24..d1584ef783 100644
--- a/avogadro/core/dihedraliterator.cpp
+++ b/avogadro/core/dihedraliterator.cpp
@@ -35,7 +35,7 @@ Dihedral DihedralIterator::begin()
       Index c = bc.second;
 
       // find an a
-      Index a;
+      Index a = 0;
       for (const auto maybeA : graph.neighbors(b)) {
         if (maybeA != c) {
           a = maybeA;
diff --git a/avogadro/core/elements.cpp b/avogadro/core/elements.cpp
index e9b9b8ab84..20ee588348 100644
--- a/avogadro/core/elements.cpp
+++ b/avogadro/core/elements.cpp
@@ -196,7 +196,7 @@ unsigned char Elements::guessAtomicNumber(const std::string& inputStr)
   str[0] = static_cast<char>(toupper(static_cast<int>(str[0])));
 
   int length = str.size();
-  unsigned char atomicNumber;
+  unsigned char atomicNumber = InvalidElement;
   while (length > 0) {
     if (length > 3)
       atomicNumber = atomicNumberFromName(str.substr(0, length));
diff --git a/avogadro/io/gromacsformat.cpp b/avogadro/io/gromacsformat.cpp
index d3e9430ee7..9ed05b4848 100644
--- a/avogadro/io/gromacsformat.cpp
+++ b/avogadro/io/gromacsformat.cpp
@@ -54,7 +54,7 @@ bool GromacsFormat::read(std::istream& in, Molecule& molecule)
 {
   string buffer;
   string value;
-  Residue* r;
+  Residue* r = nullptr;
   size_t currentResidueId = 0;
 
   // Title
@@ -138,7 +138,9 @@ bool GromacsFormat::read(std::istream& in, Molecule& molecule)
     // Atom name:
     value = trimmed(buffer.substr(10, 5));
     Atom atom;
-    int atomicNum = r->getAtomicNumber(value);
+    int atomicNum = 0;
+    if (r != nullptr)
+      r->getAtomicNumber(value);
     if (atomicNum) {
       atom = molecule.addAtom(atomicNum);
     } else {
diff --git a/avogadro/io/lammpsformat.cpp b/avogadro/io/lammpsformat.cpp
index 5c7d5a409e..c8502d7d28 100644
--- a/avogadro/io/lammpsformat.cpp
+++ b/avogadro/io/lammpsformat.cpp
@@ -426,6 +426,7 @@ bool LammpsDataFormat::write(std::ostream& outStream, const Core::Molecule& mol)
 
   std::ostringstream massStream, atomStream, bondStream;
   double xmin, xmax, ymin, ymax, zmin, zmax;
+  xmin = xmax = ymin = ymax = zmin = zmax = 0.0;
 
   size_t numAtoms = mol2.atomCount();
   outStream << to_string(numAtoms) << " atoms\n";
diff --git a/avogadro/io/pdbformat.cpp b/avogadro/io/pdbformat.cpp
index 72366ded3e..d3f7e6aacc 100644
--- a/avogadro/io/pdbformat.cpp
+++ b/avogadro/io/pdbformat.cpp
@@ -43,7 +43,7 @@ bool PdbFormat::read(std::istream& in, Core::Molecule& mol)
 {
   string buffer;
   std::vector<int> terList;
-  Residue* r;
+  Residue* r = nullptr;
   size_t currentResidueId = 0;
   bool ok(false);
   int coordSet = 0;
@@ -173,7 +173,7 @@ bool PdbFormat::read(std::istream& in, Core::Molecule& mol)
       } else if (coordSet == 0) {
         Atom newAtom = mol.addAtom(atomicNum);
         newAtom.setPosition3d(pos);
-        if (r) {
+        if (r != nullptr) {
           r->addResidueAtom(atomName, newAtom);
         }
         rawToAtomId.push_back(mol.atomCount() - 1);
diff --git a/avogadro/io/turbomoleformat.cpp b/avogadro/io/turbomoleformat.cpp
index 7722fac509..2e226f784a 100644
--- a/avogadro/io/turbomoleformat.cpp
+++ b/avogadro/io/turbomoleformat.cpp
@@ -58,6 +58,8 @@ bool TurbomoleFormat::read(std::istream& inStream, Core::Molecule& mol)
 
   // possible lattice constants
   Real a, b, c, alpha, beta, gamma;
+  a = b = c = 100.0;
+  alpha = beta = gamma = 90.0;
   // defaults if periodicity is not 3
   Vector3 v1(100.0, 0.0, 0.0);
   Vector3 v2(0.0, 100.0, 0.0);
diff --git a/avogadro/qtplugins/templatetool/templatetool.cpp b/avogadro/qtplugins/templatetool/templatetool.cpp
index 6882f601be..8263872e4f 100644
--- a/avogadro/qtplugins/templatetool/templatetool.cpp
+++ b/avogadro/qtplugins/templatetool/templatetool.cpp
@@ -370,7 +370,7 @@ void TemplateTool::atomLeftClick(QMouseEvent*)
       return;
 
     // Find dummy atom in template and get all necessary info
-    size_t templateDummyIndex;
+    size_t templateDummyIndex = 0;
     std::vector<size_t> templateLigandIndices;
     std::vector<size_t> templateLigandUIDs;
     for (size_t i = 0; i < templateMolecule.atomCount(); i++) {