diff --git a/meta/classes/base.bbclass b/meta/classes/base.bbclass
index 5f03de8247..0c7f8fcae3 100644
--- a/meta/classes/base.bbclass
+++ b/meta/classes/base.bbclass
@@ -233,25 +233,18 @@ do_build () {
 }
 
 python () {
-    import exceptions, string
+    import exceptions, string, re
 
     # If PRINC is set, try and increase the PR value by the amount specified
     princ = bb.data.getVar('PRINC', d, True)
     if princ:
         pr = bb.data.getVar('PR', d, True)
-        start = -1
-        end = -1
-        for i in range(len(pr)):
-            if pr[i] in string.digits:
-                if start == -1:
-                    start = i
-                else:
-                    end = i
-        if start == -1 or end == -1:
+        pr_prefix = re.search("\D+",pr)
+        prval = re.search("\d+",pr)
+        if pr_prefix is None or prval is None:
             bb.error("Unable to analyse format of PR variable: %s" % pr)
-        prval = pr[start:end+1]
-        prval = int(prval) + int(princ)
-        pr = pr[0:start] + str(prval) + pr[end:len(pr)-1]
+        nval = int(prval.group(0)) + int(princ)
+        pr = pr_prefix.group(0) + str(nval) + pr[prval.end():]
         bb.data.setVar('PR', pr, d)
 
     pn = bb.data.getVar('PN', d, 1)