truncate.diff

diff --git a/test-data/blank-disks/Makefile.am b/test-data/blank-disks/Makefile.am
index 2464869..ca93189 100644
--- a/test-data/blank-disks/Makefile.am
+++ b/test-data/blank-disks/Makefile.am
@@ -33,21 +33,21 @@ CLEANFILES = $(files)
 # Blank disk images in various sizes and formats.
 blank-disk-1s.raw:
 	rm -f $@
-	truncate -s 512 $@
+	gtruncate -s 512 $@
 
 blank-disk-1s.qcow2:
 	qemu-img create -f qcow2 -o preallocation=metadata $@ 512
 
 blank-disk-1K.raw:
 	rm -f $@
-	truncate -s 1K $@
+	gtruncate -s 1K $@
 
 blank-disk-1K.qcow2:
 	qemu-img create -f qcow2 -o preallocation=metadata $@ 1K
 
 blank-disk-1M.raw:
 	rm -f $@
-	truncate -s 1M $@
+	gtruncate -s 1M $@
 
 blank-disk-1M.qcow2:
 	qemu-img create -f qcow2 -o preallocation=metadata $@ 1M