diff --git a/source-builder/sb/pkgconfig.py b/source-builder/sb/pkgconfig.py
index 89b4d5c..198ec80 100755
--- a/source-builder/sb/pkgconfig.py
+++ b/source-builder/sb/pkgconfig.py
@@ -102,6 +102,22 @@ class package(object):
         dst.fields = copy.copy(src.fields)
         dst.nodes = copy.copy(src.nodes)
 
+    @staticmethod
+    def _is_string(us):
+        if type(us) == str:
+            return True
+        try:
+            if type(us) == unicode:
+                return True
+        except:
+            pass
+        try:
+            if type(us) == bytes:
+                return True
+        except:
+            pass
+        return False
+
     @staticmethod
     def is_version(v):
         for n in v.split('.'):
@@ -214,12 +230,7 @@ class package(object):
             prefix = default_prefix()
         if prefix:
             self._log('prefix: %s' % (prefix))
-            try:
-                if type(prefix) is unicode:
-                    prefix = prefix.decode("utf-8", "ignore")
-            except:
-                pass
-            if type(prefix) is str:
+            if self._is_string(prefix):
                 prefix = str(prefix)
                 self.prefix = []
                 for p in prefix.split(os.pathsep):