diff --git a/readme.md b/readme.md
index 4f20b56..a0c4397 100644
--- a/readme.md
+++ b/readme.md
@@ -2,7 +2,7 @@
 
 # mcl
 
-A generic and fast pairing-based cryptography library.
+A portable and fast pairing-based cryptography library.
 
 # Abstract
 
diff --git a/src/fp.cpp b/src/fp.cpp
index d9f3060..c720475 100644
--- a/src/fp.cpp
+++ b/src/fp.cpp
@@ -201,6 +201,7 @@ void getRandVal(Unit *out, RandGen& rg, const Unit *in, size_t bitSize)
 	if (rg.isZero()) rg = RandGen::get();
 	const size_t n = (bitSize + UnitBitSize - 1) / UnitBitSize;
 	const size_t rem = bitSize & (UnitBitSize - 1);
+	assert(n > 0);
 	for (;;) {
 		rg.read(out, n * sizeof(Unit));
 		if (rem > 0) out[n - 1] &= (Unit(1) << rem) - 1;