diff --git a/ChangeLog b/ChangeLog
index 2647d443..078ffc6c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2016-09-03 Even Rouault <even.rouault at spatialys.com>
+
+	* libtiff/tif_dirwrite.c: fix warnings raised by GCC 5 -Wfloat-conversion
+
 2016-08-16 Even Rouault <even.rouault at spatialys.com>
 
 	* tools/tiffcrop.c: fix C99'ism.
diff --git a/libtiff/tif_dirwrite.c b/libtiff/tif_dirwrite.c
index 33befd45..837fdd0f 100644
--- a/libtiff/tif_dirwrite.c
+++ b/libtiff/tif_dirwrite.c
@@ -1,4 +1,4 @@
-/* $Id: tif_dirwrite.c,v 1.81 2015-12-18 11:11:00 erouault Exp $ */
+/* $Id: tif_dirwrite.c,v 1.82 2016-09-02 22:42:00 erouault Exp $ */
 
 /*
  * Copyright (c) 1988-1997 Sam Leffler
@@ -2143,13 +2143,13 @@ TIFFWriteDirectoryTagCheckedRationalArray(TIFF* tif, uint32* ndir, TIFFDirEntry*
 		}
 		else if (*na<1.0)
 		{
-			nb[0]=(uint32)((*na)*0xFFFFFFFF);
+			nb[0]=(uint32)((double)(*na)*0xFFFFFFFF);
 			nb[1]=0xFFFFFFFF;
 		}
 		else
 		{
 			nb[0]=0xFFFFFFFF;
-			nb[1]=(uint32)(0xFFFFFFFF/(*na));
+			nb[1]=(uint32)((double)0xFFFFFFFF/(*na));
 		}
 	}
 	if (tif->tif_flags&TIFF_SWAB)
@@ -2186,13 +2186,13 @@ TIFFWriteDirectoryTagCheckedSrationalArray(TIFF* tif, uint32* ndir, TIFFDirEntry
 			}
 			else if (*na>-1.0)
 			{
-				nb[0]=-(int32)((-*na)*0x7FFFFFFF);
+				nb[0]=-(int32)((double)(-*na)*0x7FFFFFFF);
 				nb[1]=0x7FFFFFFF;
 			}
 			else
 			{
 				nb[0]=-0x7FFFFFFF;
-				nb[1]=(int32)(0x7FFFFFFF/(-*na));
+				nb[1]=(int32)((double)0x7FFFFFFF/(-*na));
 			}
 		}
 		else
@@ -2204,13 +2204,13 @@ TIFFWriteDirectoryTagCheckedSrationalArray(TIFF* tif, uint32* ndir, TIFFDirEntry
 			}
 			else if (*na<1.0)
 			{
-				nb[0]=(int32)((*na)*0x7FFFFFFF);
+				nb[0]=(int32)((double)(*na)*0x7FFFFFFF);
 				nb[1]=0x7FFFFFFF;
 			}
 			else
 			{
 				nb[0]=0x7FFFFFFF;
-				nb[1]=(int32)(0x7FFFFFFF/(*na));
+				nb[1]=(int32)((double)0x7FFFFFFF/(*na));
 			}
 		}
 	}