diff --git a/pisi/build.py b/pisi/build.py
index 69a0d0fe..2d0e709d 100644
--- a/pisi/build.py
+++ b/pisi/build.py
@@ -74,6 +74,10 @@ class PisiBuild:
 
     def build(self):
         """Build the package in one shot."""
+        if not self.spec.verify():
+            ui.err("PSPEC file is not valid")
+            raise PisiBuildError, "invalid PSPEC file %s" % self.ctx.pspecfile
+
         ui.info("Building PISI source package: %s\n" % self.spec.source.name)
 
         ui.info("Fetching source from: %s\n" % self.spec.source.archiveUri)