diff --git a/scripts/build.py b/scripts/build.py
index 60dda4ba..c3ad525b 100644
--- a/scripts/build.py
+++ b/scripts/build.py
@@ -67,7 +67,7 @@ def read_deps(cur, prereq_type):
     p = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE)
     p.wait()
     if p.returncode:
-        raise Exception("failed to get " + prereq_type + " prerequisites from " + path)
+        raise Exception("failed to get " + prereq_type + " prerequisites for " + cur + ": " + cmd)
     r = Set()
     pattern = re.compile(r'.*') # might be useful at a later point, currently pointless
     for line in iter(p.stdout.readline,''):