diff --git a/src/mkvm/vmdesc.py b/src/mkvm/vmdesc.py
index a42b388..2623d62 100644
--- a/src/mkvm/vmdesc.py
+++ b/src/mkvm/vmdesc.py
@@ -46,7 +46,7 @@ UNITS = {
 }
 
 SIZE_RE = re.compile(
-    r'^(?P<value>[0-9]+)\s*'
+    r'^(?P<value>[0-9]+(?:\.[0-9]+)?)\s*'
     r'(?P<unit>\w+)?\s*$'
 )
 
@@ -72,7 +72,7 @@ def parse_size(size):
             factor = UNITS[parts['unit']]
         except KeyError:
             raise ValueError('Invalid size : {}'.format(size))
-    return int(parts['value']) * factor
+    return int(float(parts['value']) * factor)
 
 
 class VirtualMachine(object):