diff --git a/examples/osgautocapture/osgautocapture.cpp b/examples/osgautocapture/osgautocapture.cpp
index 75a5b568c..b9366266e 100644
--- a/examples/osgautocapture/osgautocapture.cpp
+++ b/examples/osgautocapture/osgautocapture.cpp
@@ -99,7 +99,7 @@ public:
 #if defined(OSG_GLES1_AVAILABLE) || defined(OSG_GLES2_AVAILABLE)
                  if (pixelFormat == GL_RGB)
                  {
-                    GLint value;
+                    GLint value = 0;
                     #ifndef GL_IMPLEMENTATION_COLOR_READ_FORMAT
                         #define GL_IMPLEMENTATION_COLOR_READ_FORMAT 0x8B9B
                     #endif
diff --git a/src/osg/FragmentProgram.cpp b/src/osg/FragmentProgram.cpp
index 9e9aab4f9..bf2a7344a 100644
--- a/src/osg/FragmentProgram.cpp
+++ b/src/osg/FragmentProgram.cpp
@@ -150,7 +150,7 @@ void FragmentProgram::apply(State& state) const
                                      _fragmentProgram.length(), _fragmentProgram.c_str());
 
         // Check for errors
-        GLint errorposition;
+        GLint errorposition = 0;
         glGetIntegerv(GL_PROGRAM_ERROR_POSITION_ARB, &errorposition);
         if (errorposition != -1)
         {
diff --git a/src/osg/GLExtensions.cpp b/src/osg/GLExtensions.cpp
index 10b93a595..34e5beb1f 100644
--- a/src/osg/GLExtensions.cpp
+++ b/src/osg/GLExtensions.cpp
@@ -129,7 +129,7 @@ bool osg::isGLExtensionOrVersionSupported(unsigned int contextID, const char *ex
                     #  ifndef GL_NUM_EXTENSIONS
                     #    define GL_NUM_EXTENSIONS 0x821D
                     #  endif
-                    GLint numExt;
+                    GLint numExt = 0;
                     glGetIntegerv( GL_NUM_EXTENSIONS, &numExt );
                     int idx;
                     for( idx=0; idx<numExt; idx++ )
diff --git a/src/osg/Shader.cpp b/src/osg/Shader.cpp
index de828d497..c7b273553 100644
--- a/src/osg/Shader.cpp
+++ b/src/osg/Shader.cpp
@@ -503,7 +503,7 @@ void Shader::PerContextShader::compileShader(osg::State& state)
 #if defined(OSG_GLES2_AVAILABLE)
     if (_shader->getShaderBinary())
     {
-        GLint numFormats;
+        GLint numFormats = 0;
         glGetIntegerv(GL_NUM_SHADER_BINARY_FORMATS, &numFormats);
 
         if (numFormats>0)
diff --git a/src/osg/State.cpp b/src/osg/State.cpp
index e89c7b001..cebcf0d1b 100644
--- a/src/osg/State.cpp
+++ b/src/osg/State.cpp
@@ -899,7 +899,7 @@ void State::initializeExtensionProcs()
                                  osg::isGLExtensionSupported(_contextID,"GL_EXT_multitexture") ||
                                  OSG_GLES1_FEATURES)
     {
-        GLint maxTextureUnits;
+        GLint maxTextureUnits = 0;
         glGetIntegerv(GL_MAX_TEXTURE_UNITS,&maxTextureUnits);
         _glMaxTextureUnits = maxTextureUnits;
         _glMaxTextureCoords = maxTextureUnits;
diff --git a/src/osg/Texture.cpp b/src/osg/Texture.cpp
index 9630faf74..d5f3d40da 100644
--- a/src/osg/Texture.cpp
+++ b/src/osg/Texture.cpp
@@ -2258,6 +2258,7 @@ Texture::Extensions::Extensions(unsigned int contextID)
         OSG_INFO<<"Disabling _isNonPowerOfTwoTextureMipMappedSupported for GeForce FX hardware."<<std::endl;
     }
 
+    _maxTextureSize=0;
     glGetIntegerv(GL_MAX_TEXTURE_SIZE,&_maxTextureSize);
 
     char *ptr;
@@ -2274,6 +2275,7 @@ Texture::Extensions::Extensions(unsigned int contextID)
 
     if( _isMultiTexturingSupported )
     {
+       _numTextureUnits = 0;
        #if defined(OSG_GLES2_AVAILABLE) || defined(OSG_GL3_AVAILABLE)
            glGetIntegerv(GL_MAX_TEXTURE_IMAGE_UNITS,&_numTextureUnits);
        #else
diff --git a/src/osg/Texture2DArray.cpp b/src/osg/Texture2DArray.cpp
index 1c87b50a6..5579e191d 100644
--- a/src/osg/Texture2DArray.cpp
+++ b/src/osg/Texture2DArray.cpp
@@ -711,7 +711,9 @@ void Texture2DArray::Extensions::setupGLExtensions(unsigned int contextID)
     _isTexture3DSupported = OSG_GL3_FEATURES || isGLExtensionSupported(contextID,"GL_EXT_texture3D");
     _isTexture2DArraySupported = OSG_GL3_FEATURES || isGLExtensionSupported(contextID,"GL_EXT_texture_array");
 
+    _max2DSize = 0;
     glGetIntegerv(GL_MAX_TEXTURE_SIZE, &_max2DSize);
+    _maxLayerCount = 0;
     glGetIntegerv(GL_MAX_ARRAY_TEXTURE_LAYERS_EXT, &_maxLayerCount);
 
     setGLExtensionFuncPtr(_glTexImage3D, "glTexImage3D","glTexImage3DEXT");
diff --git a/src/osg/Texture3D.cpp b/src/osg/Texture3D.cpp
index 3d88bc034..84e46cfa7 100644
--- a/src/osg/Texture3D.cpp
+++ b/src/osg/Texture3D.cpp
@@ -606,6 +606,7 @@ void Texture3D::Extensions::setupGLExtensions(unsigned int contextID)
     if (_isTexture3DFast) _isTexture3DSupported = true;
     else _isTexture3DSupported = strncmp((const char*)glGetString(GL_VERSION),"1.2",3)>=0;
     
+    _maxTexture3DSize = 0;
     glGetIntegerv(GL_MAX_3D_TEXTURE_SIZE, &_maxTexture3DSize);
 
     setGLExtensionFuncPtr(glTexImage3D,"glTexImage3D","glTexImage3DEXT");
diff --git a/src/osg/VertexProgram.cpp b/src/osg/VertexProgram.cpp
index 1ead4bf5d..1e70c45bc 100644
--- a/src/osg/VertexProgram.cpp
+++ b/src/osg/VertexProgram.cpp
@@ -150,7 +150,7 @@ void VertexProgram::apply(State& state) const
                                      _vertexProgram.length(), _vertexProgram.c_str());
 
         // Check for errors
-        GLint errorposition;
+        GLint errorposition = 0;
         glGetIntegerv(GL_PROGRAM_ERROR_POSITION_ARB, &errorposition);
         if (errorposition != -1)
         {