diff --git a/README b/README
index 759d61715eac15788694b89fc68ea9ef85085091..5bc67f109adf7d2a6511435f7654c06a4836a47e 100644
--- a/README
+++ b/README
@@ -6,7 +6,7 @@ __________________________
 A valid version is an integer without dot.
 A version n, may be followed by a ~, to indicate it's inferior to n
 A version n, may be followed by a +, to indicate it's superior to n
-Any following ascii chars after ~ or + are ignored
+Any following chars after ~ or + are ignored
 
 Examples:
   1 < 2
diff --git a/installsystems/tools.py b/installsystems/tools.py
index 2269f97f5ac1ade06588b33d8761c387187be4cc..713dd35544e0e32c6af1c45fcd1a4462534cfdb2 100644
--- a/installsystems/tools.py
+++ b/installsystems/tools.py
@@ -478,9 +478,9 @@ def compare_versions(v1, v2):
         if type(version) is int or type(version) is float:
             return float(version)
         elif isinstance(version, basestring):
-            iv = re.match("^(\d+)(?:([-~+])\w*)?$", version)
+            iv = re.match("^(\d+)(?:([-~+]).*)?$", version)
             if iv is None:
-                raise TypeError('Invalid version: %s' % version)
+                raise TypeError('Invalid version format: %s' % version)
             rv = float(iv.group(1))
             if iv.group(2) == "~":
                 rv -= 0.1
@@ -488,7 +488,7 @@ def compare_versions(v1, v2):
                 rv += 0.1
             return rv
         else:
-            raise TypeError('Invalid version: %s' % version)
+            raise TypeError('Invalid version format: %s' % version)
 
     fv1 = get_ver(v1)
     fv2 = get_ver(v2)