diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 36b8f3cb7fd20062b817731604bd47ef39b90ad9..92e34076326d266e0ed7cbbea63c523422bbe98e 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -1623,6 +1623,46 @@ qemuBuildDriveSourceStr(virDomainDiskDefPtr disk,
 }
 
 
+static void
+qemuBuildDiskThrottling(virDomainDiskDefPtr disk,
+                        virBufferPtr buf)
+{
+#define IOTUNE_ADD(_field, _label) \
+    if (disk->blkdeviotune._field) { \
+        virBufferAsprintf(buf, ",throttling." _label "=%llu", \
+                          disk->blkdeviotune._field); \
+    }
+
+    IOTUNE_ADD(total_bytes_sec, "bps-total");
+    IOTUNE_ADD(read_bytes_sec, "bps-read");
+    IOTUNE_ADD(write_bytes_sec, "bps-write");
+    IOTUNE_ADD(total_iops_sec, "iops-total");
+    IOTUNE_ADD(read_iops_sec, "iops-read");
+    IOTUNE_ADD(write_iops_sec, "iops-write");
+
+    IOTUNE_ADD(total_bytes_sec_max, "bps-total-max");
+    IOTUNE_ADD(read_bytes_sec_max, "bps-read-max");
+    IOTUNE_ADD(write_bytes_sec_max, "bps-write-max");
+    IOTUNE_ADD(total_iops_sec_max, "iops-total-max");
+    IOTUNE_ADD(read_iops_sec_max, "iops-read-max");
+    IOTUNE_ADD(write_iops_sec_max, "iops-write-max");
+
+    IOTUNE_ADD(size_iops_sec, "iops-size");
+    if (disk->blkdeviotune.group_name) {
+        virBufferEscapeString(buf, ",throttling.group=%s",
+                              disk->blkdeviotune.group_name);
+    }
+
+    IOTUNE_ADD(total_bytes_sec_max_length, "bps-total-max-length");
+    IOTUNE_ADD(read_bytes_sec_max_length, "bps-read-max-length");
+    IOTUNE_ADD(write_bytes_sec_max_length, "bps-write-max-length");
+    IOTUNE_ADD(total_iops_sec_max_length, "iops-total-max-length");
+    IOTUNE_ADD(read_iops_sec_max_length, "iops-read-max-length");
+    IOTUNE_ADD(write_iops_sec_max_length, "iops-write-max-length");
+#undef IOTUNE_ADD
+}
+
+
 static void
 qemuBuildDiskFrontendAttributes(virDomainDiskDefPtr disk,
                                 virQEMUCapsPtr qemuCaps,
@@ -1776,40 +1816,7 @@ qemuBuildDriveStr(virDomainDiskDefPtr disk,
                           virDomainDiskIoTypeToString(disk->iomode));
     }
 
-#define IOTUNE_ADD(_field, _label) \
-    if (disk->blkdeviotune._field) { \
-        virBufferAsprintf(&opt, ",throttling." _label "=%llu", \
-                           disk->blkdeviotune._field); \
-    }
-
-    IOTUNE_ADD(total_bytes_sec, "bps-total");
-    IOTUNE_ADD(read_bytes_sec, "bps-read");
-    IOTUNE_ADD(write_bytes_sec, "bps-write");
-    IOTUNE_ADD(total_iops_sec, "iops-total");
-    IOTUNE_ADD(read_iops_sec, "iops-read");
-    IOTUNE_ADD(write_iops_sec, "iops-write");
-
-    IOTUNE_ADD(total_bytes_sec_max, "bps-total-max");
-    IOTUNE_ADD(read_bytes_sec_max, "bps-read-max");
-    IOTUNE_ADD(write_bytes_sec_max, "bps-write-max");
-    IOTUNE_ADD(total_iops_sec_max, "iops-total-max");
-    IOTUNE_ADD(read_iops_sec_max, "iops-read-max");
-    IOTUNE_ADD(write_iops_sec_max, "iops-write-max");
-
-    IOTUNE_ADD(size_iops_sec, "iops-size");
-    if (disk->blkdeviotune.group_name) {
-        virBufferEscapeString(&opt, ",throttling.group=%s",
-                              disk->blkdeviotune.group_name);
-    }
-
-    IOTUNE_ADD(total_bytes_sec_max_length, "bps-total-max-length");
-    IOTUNE_ADD(read_bytes_sec_max_length, "bps-read-max-length");
-    IOTUNE_ADD(write_bytes_sec_max_length, "bps-write-max-length");
-    IOTUNE_ADD(total_iops_sec_max_length, "iops-total-max-length");
-    IOTUNE_ADD(read_iops_sec_max_length, "iops-read-max-length");
-    IOTUNE_ADD(write_iops_sec_max_length, "iops-write-max-length");
-
-#undef IOTUNE_ADD
+    qemuBuildDiskThrottling(disk, &opt);
 
     if (virBufferCheckError(&opt) < 0)
         goto error;