diff --git a/panda/src/pnmimagetypes/pnmFileTypeBMPReader.cxx b/panda/src/pnmimagetypes/pnmFileTypeBMPReader.cxx
index 7077933395..6d1ac43a61 100644
--- a/panda/src/pnmimagetypes/pnmFileTypeBMPReader.cxx
+++ b/panda/src/pnmimagetypes/pnmFileTypeBMPReader.cxx
@@ -179,12 +179,12 @@ BMPreadinfoheader(
         int            *pclassv)
 {
         unsigned long   cbFix;
-        unsigned short  cPlanes;
+        unsigned short  cPlanes = 0;
 
-        unsigned long   cx;
-        unsigned long   cy;
-        unsigned short  cBitCount;
-        int             classv;
+        unsigned long   cx = 0;
+        unsigned long   cy = 0;
+        unsigned short  cBitCount = 0;
+        int             classv = 0;
 
         cbFix = GetLong(fp);
 
@@ -315,7 +315,7 @@ BMPreadrow(
         pixval         *G,
         pixval         *B)
 {
-        BITSTREAM       b;
+        BITSTREAM       b = NULL;
         unsigned        nbyte = 0;
         int             rc;
         unsigned        x;
diff --git a/panda/src/pnmimagetypes/pnmFileTypeBMPWriter.cxx b/panda/src/pnmimagetypes/pnmFileTypeBMPWriter.cxx
index 9099c6a147..2d48840330 100644
--- a/panda/src/pnmimagetypes/pnmFileTypeBMPWriter.cxx
+++ b/panda/src/pnmimagetypes/pnmFileTypeBMPWriter.cxx
@@ -143,7 +143,7 @@ BMPwriteinfoheader(
         unsigned long   x,
         unsigned long   y)
 {
-        long    cbFix;
+        long    cbFix = 0;
 
         /* cbFix */
         switch (classv)
diff --git a/panda/src/pnmimagetypes/pnmFileTypeJPG.h b/panda/src/pnmimagetypes/pnmFileTypeJPG.h
index 3d6e330587..7a152248b5 100644
--- a/panda/src/pnmimagetypes/pnmFileTypeJPG.h
+++ b/panda/src/pnmimagetypes/pnmFileTypeJPG.h
@@ -31,6 +31,14 @@
 #include <windows.h>  // we need to include this before jpeglib.
 #endif
 
+#ifdef HAVE_PNG
+// If we are going to be including png.h (in the unrelated file
+// pnmFileTypePNG.h), be sure to include it before including setjmp.h.
+// Ugly hack due to png weirdness with setjmp.
+#include <png.h>
+#endif
+
+
 extern "C" {
 #include <stdio.h>  // jpeglib requires this to be included first.
 #include <jpeglib.h>
diff --git a/panda/src/pnmimagetypes/pnmFileTypePNG.cxx b/panda/src/pnmimagetypes/pnmFileTypePNG.cxx
index ee5b908209..39ec9bb441 100755
--- a/panda/src/pnmimagetypes/pnmFileTypePNG.cxx
+++ b/panda/src/pnmimagetypes/pnmFileTypePNG.cxx
@@ -351,7 +351,10 @@ read_data(xel *array, xelval *alpha_data) {
   for (yi = 0; yi < num_rows; yi++) {
     png_bytep source = rows[yi];
     for (int xi = 0; xi < _x_size; xi++) {
-      int red, green, blue, alpha;
+      int red = 0;
+      int green = 0;
+      int blue = 0;
+      int alpha = 0;
 
       if (_maxval > 255) {
         if (get_color) {
@@ -430,7 +433,7 @@ void PNMFileTypePNG::Reader::
 png_read_data(png_structp png_ptr, png_bytep data, png_size_t length) {
   Reader *self = (Reader *)png_get_io_ptr(png_ptr);
   self->_file->read((char *)data, length);
-  if (self->_file->gcount() != length) {
+  if (length != (png_size_t)self->_file->gcount()) {
     pnmimage_png_cat.error()
       << "Didn't read enough bytes.\n";
     // Is there no way to indicate a read failure to libpng?
diff --git a/panda/src/pnmimagetypes/pnmFileTypeSGIReader.cxx b/panda/src/pnmimagetypes/pnmFileTypeSGIReader.cxx
index c421efcb28..65aeb23aa7 100644
--- a/panda/src/pnmimagetypes/pnmFileTypeSGIReader.cxx
+++ b/panda/src/pnmimagetypes/pnmFileTypeSGIReader.cxx
@@ -346,7 +346,7 @@ read_channel(istream *ifp,
              TabEntry *table,
              ScanElem *channel_data, long table_start,
              int channel, int row) {
-    ScanElem *temp;
+    ScanElem *temp = NULL;
     int sgi_index, i;
     long offset, length;
 
diff --git a/panda/src/pnmimagetypes/pnmFileTypeTGA.cxx b/panda/src/pnmimagetypes/pnmFileTypeTGA.cxx
index cbb0b09f1a..63ee5960c9 100644
--- a/panda/src/pnmimagetypes/pnmFileTypeTGA.cxx
+++ b/panda/src/pnmimagetypes/pnmFileTypeTGA.cxx
@@ -646,43 +646,44 @@ readtga( istream *ifp, struct ImageHeader *tgaP, const string &magic_number ) {
 
 void PNMFileTypeTGA::Reader::
 get_map_entry( istream *ifp, pixel *Value, int Size, gray *Alpha ) {
-    unsigned char j, k, r, g, b, a;
+    unsigned char j, k;
+    unsigned char r = 0, g = 0, b = 0, a = 0;
 
     /* Read appropriate number of bytes, break into rgb & put in map. */
     switch ( Size )
-        {
-        case 8:                         /* Grey scale, read and triplicate. */
+      {
+      case 8:                         /* Grey scale, read and triplicate. */
         r = g = b = getbyte( ifp );
-    a = 0;
+        a = 0;
         break;
-
-        case 16:                        /* 5 bits each of red green and blue. */
-        case 15:                        /* Watch for byte order. */
+        
+      case 16:                        /* 5 bits each of red green and blue. */
+      case 15:                        /* Watch for byte order. */
         j = getbyte( ifp );
         k = getbyte( ifp );
         r = ( k & 0x7C ) >> 2;
         g = ( ( k & 0x03 ) << 3 ) + ( ( j & 0xE0 ) >> 5 );
         b = j & 0x1F;
-    a = 0;
+        a = 0;
         break;
 
-        case 32:            /* 8 bits each of blue, green, red, and alpha */
-        case 24:                        /* 8 bits each of blue green and red. */
+      case 32:            /* 8 bits each of blue, green, red, and alpha */
+      case 24:                        /* 8 bits each of blue green and red. */
         b = getbyte( ifp );
         g = getbyte( ifp );
         r = getbyte( ifp );
         if ( Size == 32 )
-            a = getbyte( ifp );
-    else
-        a = 0;
+          a = getbyte( ifp );
+        else
+          a = 0;
         break;
-
-        default:
+        
+      default:
         pm_error( "unknown colormap pixel size (#2) - %d", Size );
-        }
+      }
     PPM_ASSIGN( *Value, r, g, b );
     *Alpha = a;
-    }
+}