diff --git a/CHANGES b/CHANGES
index 647a6ec3de..2488227d58 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,4 +1,9 @@
 
+2.3-427 | 2015-02-20 13:49:33 -0800
+
+  * Removing dependency on PCAP_NETMASK_UNKNOWN to compile with
+    libpcap < 1.1.1. (Robin Sommer)
+
 2.3-426 | 2015-02-20 12:45:51 -0800
 
   * Add 'while' statement to Bro language. Really. (Jon Siwek)
diff --git a/VERSION b/VERSION
index 07a0bd75a8..ceb17112a6 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.3-426
+2.3-427
diff --git a/src/iosource/PktSrc.cc b/src/iosource/PktSrc.cc
index 527dadd393..5612c32e51 100644
--- a/src/iosource/PktSrc.cc
+++ b/src/iosource/PktSrc.cc
@@ -13,6 +13,15 @@
 
 using namespace iosource;
 
+PktSrc::Properties::Properties()
+	{
+	selectable_fd = -1;
+	link_type = -1;
+	hdr_size = -1;
+	netmask = NETMASK_UNKNOWN;
+	is_live = false;
+	}
+
 PktSrc::PktSrc()
 	{
 	have_packet = false;
@@ -50,7 +59,7 @@ int PktSrc::LinkType() const
 
 uint32 PktSrc::Netmask() const
 	{
-	return IsOpen() ? props.netmask : PCAP_NETMASK_UNKNOWN;
+	return IsOpen() ? props.netmask : NETMASK_UNKNOWN;
 	}
 
 bool PktSrc::IsError() const
diff --git a/src/iosource/PktSrc.h b/src/iosource/PktSrc.h
index 7137798129..378ac3f5ee 100644
--- a/src/iosource/PktSrc.h
+++ b/src/iosource/PktSrc.h
@@ -16,6 +16,8 @@ namespace iosource {
  */
 class PktSrc : public IOSource {
 public:
+	static const int NETMASK_UNKNOWN = 0xffffffff;
+
 	/**
 	 * Struct for returning statistics on a packet source.
 	 */
@@ -67,7 +69,7 @@ public:
 
 	/**
 	 * Returns the netmask associated with the source, or \c
-	 * PCAP_NETMASK_UNKNOWN if unknown.
+	 * NETMASK_UNKNOWN if unknown.
 	 */
 	uint32 Netmask() const;
 
@@ -253,8 +255,8 @@ protected:
 		int hdr_size;
 
 		/**
-		 * The netmask associated with the source, or \c
-		 * PCAP_NETMASK_UNKNOWN if unknown.
+		 * Returns the netmask associated with the source, or \c
+		 * NETMASK_UNKNOWN if unknown.
 		 */
 		uint32 netmask;
 
@@ -264,14 +266,7 @@ protected:
 		 */
 		bool is_live;
 
-		Properties()
-			{
-			selectable_fd = -1;
-			link_type = -1;
-			hdr_size = -1;
-			netmask = PCAP_NETMASK_UNKNOWN;
-			is_live = false;
-			}
+		Properties();
 	};
 
 	/**
diff --git a/src/iosource/pcap/Source.cc b/src/iosource/pcap/Source.cc
index 72b19b2f14..a68f0ca322 100644
--- a/src/iosource/pcap/Source.cc
+++ b/src/iosource/pcap/Source.cc
@@ -77,6 +77,12 @@ void PcapSource::OpenLive()
 		props.netmask = 0xffffff00;
 		}
 
+#ifdef PCAP_NETMASK_UNKNOWN
+	// Defined in libpcap >= 1.1.1
+	if ( props.netmask == PCAP_NETMASK_UNKNOWN )
+		props.netmask = PktSrc::NETMASK_UNKNOWN;
+#endif
+
 	// We use the smallest time-out possible to return almost immediately if
 	// no packets are available. (We can't use set_nonblocking() as it's
 	// broken on FreeBSD: even when select() indicates that we can read