diff --git a/src/osg/glu/libutil/mipmap.cpp b/src/osg/glu/libutil/mipmap.cpp
index bec349c4c..28a219e99 100644
--- a/src/osg/glu/libutil/mipmap.cpp
+++ b/src/osg/glu/libutil/mipmap.cpp
@@ -4965,7 +4965,7 @@ static void fill_image(const PixelStorageModes *psm,
     GLint group_size;
     GLint elements_per_line;
     const GLubyte *start;
-    const GLubyte *iter;
+    const GLubyte *iter = NULL;
     GLushort *iter2;
     GLint i, j, k;
     GLint myswap_bytes;
@@ -5228,7 +5228,7 @@ static void empty_image(const PixelStorageModes *psm,
     GLint group_size;
     GLint elements_per_line;
     GLubyte *start;
-    GLubyte *iter;
+    GLubyte *iter = NULL;
     const GLushort *iter2;
     GLint i, j, k;
     GLint myswap_bytes;
@@ -6713,7 +6713,7 @@ static void fillImage3D(const PixelStorageModes *psm,
    int elementsPerLine;
    int rowsPerImage;
    int imageSize;
-   const GLubyte *start, *rowStart, *iter;
+   const GLubyte *start, *rowStart, *iter = NULL;
    GLushort *iter2;
    int ww, hh, dd, k;
 
@@ -7075,7 +7075,7 @@ static void emptyImage3D(const PixelStorageModes *psm,
    int groupSize;
    int rowSize;
    int padding;
-   GLubyte *start, *rowStart, *iter;
+   GLubyte *start, *rowStart, *iter = NULL;
    int elementsPerLine;
    const GLushort *iter2;
    int ii, jj, dd, k;
@@ -8983,4 +8983,4 @@ static void halveImage3D(int components,
 
 /*** mipmap.c ***/
 
-} // end of namespace osg
\ No newline at end of file
+} // end of namespace osg