diff --git a/scripts/base/init-bare.zeek b/scripts/base/init-bare.zeek
index 9045370db9..ce7e815a78 100644
--- a/scripts/base/init-bare.zeek
+++ b/scripts/base/init-bare.zeek
@@ -996,7 +996,7 @@ const UDP_ACTIVE = 1;	##< Endpoint has sent something.
 const ignore_checksums = F &redef;
 
 ## Checksums are ignored for all packets with a src address within this set of
-## addresses. Useful for cases where a host might be seeing packets collected 
+## networks. Useful for cases where a host might be seeing packets collected 
 ## from local hosts before checksums were applied by hardware. This frequently 
 ## manifests when sniffing a local management interface on a host and Zeek sees
 ## packets before the hardware has had a chance to apply the checksums.
diff --git a/src/Val.cc b/src/Val.cc
index 419742f300..66e8b8d568 100644
--- a/src/Val.cc
+++ b/src/Val.cc
@@ -1991,9 +1991,15 @@ ValPtr TableVal::FindOrDefault(const ValPtr& index)
 	return Default(index);
 	}
 
-bool TableVal::Contains(const IPAddr& addr)
+const bool TableVal::Contains(const IPAddr& addr)
 	{
-	return subnets ? subnets->Lookup(addr, true) != 0 : false;
+        if ( ! subnets )
+		{
+                reporter->InternalError("LookupSubnets called on wrong table type");
+		return false;
+		}
+
+	return (subnets->Lookup(addr, true) != 0);
 	}
 
 Val* TableVal::Lookup(Val* index, bool use_default_val)
diff --git a/src/Val.h b/src/Val.h
index a38aae2c08..104bbb2e97 100644
--- a/src/Val.h
+++ b/src/Val.h
@@ -906,9 +906,15 @@ public:
 	[[deprecated("Remove in v4.1.  Use Find() or FindOrDefault().")]]
 	Val* Lookup(Val* index, bool use_default_val = true);
 
-	// Returns true if this is a table[subnet]/set[subnet] and the
-	// given address was found in the table. Otherwise returns false.
-	bool Contains(const IPAddr& addr);
+	/**
+	 * Returns true if this is a table[subnet]/set[subnet] and the
+	 * given address was found in the table. Otherwise returns false.
+	 * @param addr  The address to look for.
+	 * @return  Boolean value to indicate if addr is in the table or set. If
+	 * self is not a table[subnet]/set[subnet] an internal error will be 
+	 * generated and false will be returned.
+	 */
+	bool Contains(const IPAddr& addr) const;
 
 	// For a table[subnet]/set[subnet], return all subnets that cover
 	// the given subnet.