diff --git a/tools/psdpng.c b/tools/psdpng.c
index adf1f2d..5170c8c 100644
--- a/tools/psdpng.c
+++ b/tools/psdpng.c
@@ -162,7 +162,7 @@ void transform_signal(void)
         if (++avgctr == navg) {
             avgctr=0;
             ++nrows;
-            vals = (float*)realloc(vals,sizeof(float)*nrows*nfreqs);
+            CHECKNULL( vals = (float*)realloc(vals,sizeof(float)*nrows*nfreqs) );
             float eps = 1;
             for (i=0;i<nfreqs;++i)
                 vals[(nrows - 1) * nfreqs + i] = 10 * log10 ( mag2buf[i] / navg + eps );
@@ -196,10 +196,10 @@ void make_png(void)
     png_set_IHDR(png_ptr, info_ptr ,nfreqs,nrows,8,PNG_COLOR_TYPE_RGB,PNG_INTERLACE_NONE,PNG_COMPRESSION_TYPE_DEFAULT,PNG_FILTER_TYPE_DEFAULT );
     
 
-    row_data = (rgb_t*)malloc(sizeof(rgb_t) * nrows * nfreqs) ;
+    CHECKNULL( row_data = (rgb_t*)malloc(sizeof(rgb_t) * nrows * nfreqs) );
     cpx2pixels(row_data, vals, nfreqs*nrows );
 
-    row_pointers = realloc(row_pointers, nrows*sizeof(png_bytep));
+    CHECKNULL( row_pointers = malloc(nrows*sizeof(png_bytep)) );
     for (i=0;i<nrows;++i) {
         row_pointers[i] = (png_bytep)(row_data + i*nfreqs);
     }