diff --git a/rtengine/dcraw.cc b/rtengine/dcraw.cc
index dcfe66ee5..4daf451d0 100644
--- a/rtengine/dcraw.cc
+++ b/rtengine/dcraw.cc
@@ -9727,10 +9727,28 @@ static void copyFloatDataToInt(float * src, ushort * dst, size_t size, float max
 }
 
 void CLASS deflate_dng_load_raw() {
+    float_raw_image = new float[raw_width * raw_height];
+
+#ifdef _OPENMP
+#pragma omp parallel for
+#endif
+    for (size_t i = 0; i < raw_width * raw_height; ++i)
+      float_raw_image[i] = 0.0f;
+
+  if(tiff_samples != 1) {
+    fprintf(stderr, "deflate_dng_load_raw %s: demosaiced float dng files are not supported\n",ifname);
+    return;
+  }
+
   struct tiff_ifd * ifd = &tiff_ifd[0];
   while (ifd < &tiff_ifd[tiff_nifds] && ifd->offset != data_offset) ++ifd;
   if (ifd == &tiff_ifd[tiff_nifds]) {
-    fprintf(stderr, "DNG Deflate: Raw image not found???\n");
+    fprintf(stderr, "deflate_dng_load_raw %s: Raw image not found???\n",ifname);
+    return;
+  }
+
+  if (ifd->sample_format != 3) {  // no floating point data
+    fprintf(stderr, "deflate_dng_load_raw %s: Only float format is supported for deflate compressed dng files\n",ifname);
     return;
   }
 
@@ -9742,16 +9760,6 @@ void CLASS deflate_dng_load_raw() {
 	default: predFactor = 0; break;
   }
 
-  if (ifd->sample_format == 3) {  // Floating point data
-    float_raw_image = new float[raw_width * raw_height];
-
-#ifdef _OPENMP
-#pragma omp parallel for
-#endif
-    for (size_t i = 0; i < raw_width * raw_height; ++i)
-      float_raw_image[i] = 0.0f;
-  }
-
   // NOTE: This reader is based on the official DNG SDK from Adobe.
   // It assumes tiles without subtiles, but the standard does not say that
   // subtiles or strips couldn't be used.
diff --git a/rtengine/dcraw.patch.README b/rtengine/dcraw.patch.README
index 22b2323d7..7d2c6dc4f 100644
--- a/rtengine/dcraw.patch.README
+++ b/rtengine/dcraw.patch.README
@@ -1,8 +1,7 @@
 Patch for vanilla dcraw.  Please run this against any new dcraw version copied here.
  Instructions for patching:
-1) Download newest dcraw.c file, and copy to this folder.
-2) Run 'patch -p0 < dcraw.patch' to patch the file.  If there are any rejections, please fix them manually.
-3) Move the patched dcraw.c to dcraw.cc
-4) Re-copy the vanilla downloaded dcraw.c back to this folder, and update the patch: 'diff -u dcraw.c dcraw.cc > dcraw.patch'
-
 
+1) Create the patch: 'diff -u dcraw.c dcraw.cc > dcraw.patch'
+2) Download newest dcraw.c file, and copy to this folder.
+3) Run 'patch -p0 < dcraw.patch' to patch the file.  If there are any rejections, please fix them manually.
+4) Move the patched dcraw.c to dcraw.cc