Index: src/OFSystemInfo.h
==================================================================
--- src/OFSystemInfo.h
+++ src/OFSystemInfo.h
@@ -19,10 +19,36 @@
 OF_ASSUME_NONNULL_BEGIN
 
 @class OFDictionary OF_GENERIC(KeyType, ObjectType);
 @class OFIRI;
 
+#ifdef OF_HAVE_SOCKETS
+/**
+ * @brief A dictionary describing a network interface, as returned by
+ *	  @ref networkInterfaces.
+ *
+ * Keys are of type @ref OFNetworkInterfaceKey.
+ */
+typedef OFDictionary OF_GENERIC(OFString *, id) *OFNetworkInterface;
+
+/**
+ * @brief A key of an @ref OFNetworkInterface.
+ *
+ * Possible values are:
+ *
+ *   * @ref OFNetworkInterfaceIndex
+ */
+typedef OFConstantString *OFNetworkInterfaceKey;
+
+/**
+ * @brief The index of a network interface.
+ *
+ * This maps to a @ref OFNumber.
+ */
+extern OFNetworkInterfaceKey OFNetworkInterfaceIndex;
+#endif
+
 /**
  * @class OFSystemInfo OFSystemInfo.h ObjFW/OFSystemInfo.h
  *
  * @brief A class for querying information about the system.
  */
@@ -63,11 +89,11 @@
 # ifdef OF_WINDOWS
 @property (class, readonly, nonatomic, getter=isWindowsNT) bool windowsNT;
 # endif
 # ifdef OF_HAVE_SOCKETS
 @property (class, readonly, nullable, nonatomic)
-    OFArray OF_GENERIC(OFString *) *networkInterfaces;
+    OFDictionary OF_GENERIC(OFString *, OFNetworkInterface) *networkInterfaces;
 # endif
 #endif
 
 /**
  * @brief Returns the size of a page.
@@ -348,13 +374,14 @@
  * @brief Returns the available (though not necessarily configured) network
  *	  interfaces.
  *
  * @return The available network interfaces
  */
-+ (nullable OFArray OF_GENERIC(OFString *) *)networkInterfaces;
++ (nullable OFDictionary OF_GENERIC(OFString *, OFNetworkInterface) *)
+    networkInterfaces;
 #endif
 
 + (instancetype)alloc OF_UNAVAILABLE;
 - (instancetype)init OF_UNAVAILABLE;
 @end
 
 OF_ASSUME_NONNULL_END

Index: src/OFSystemInfo.m
==================================================================
--- src/OFSystemInfo.m
+++ src/OFSystemInfo.m
@@ -122,10 +122,14 @@
 extern NSSearchPathEnumerationState NSStartSearchPathEnumeration(
     NSSearchPathDirectory, NSSearchPathDomainMask);
 extern NSSearchPathEnumerationState NSGetNextSearchPathEnumeration(
     NSSearchPathEnumerationState, char *);
 #endif
+
+#ifdef OF_HAVE_SOCKETS
+OFNetworkInterfaceKey OFNetworkInterfaceIndex = @"OFNetworkInterfaceIndex";
+#endif
 
 #if defined(OF_AMD64) || defined(OF_X86)
 struct X86Regs {
 	uint32_t eax, ebx, ecx, edx;
 };
@@ -837,14 +841,14 @@
 	return !(GetVersion() & 0x80000000);
 }
 #endif
 
 #ifdef OF_HAVE_SOCKETS
-+ (OFArray OF_GENERIC(OFString *) *)networkInterfaces
++ (OFDictionary OF_GENERIC(OFString *, OFNetworkInterface) *)networkInterfaces
 {
 # ifdef HAVE_IF_NAMEINDEX
-	OFMutableArray *ret = [OFMutableArray array];
+	OFMutableDictionary *ret = [OFMutableDictionary dictionary];
 	void *pool = objc_autoreleasePoolPush();
 	OFStringEncoding encoding = [OFLocale encoding];
 	struct if_nameindex *nameindex = if_nameindex();
 
 	if (nameindex == NULL) {
@@ -851,14 +855,22 @@
 		objc_autoreleasePoolPop(pool);
 		return nil;
 	}
 
 	@try {
-		for (size_t i = 0; nameindex[i].if_index != 0; i++)
-			[ret addObject: [OFString
+		for (size_t i = 0; nameindex[i].if_index != 0; i++) {
+			OFString *name = [OFString
 			    stringWithCString: nameindex[i].if_name
-				     encoding: encoding]];
+				     encoding: encoding];
+			OFNumber *index = [OFNumber
+			    numberWithUnsignedInt: nameindex[i].if_index];
+			OFDictionary *interface = [OFDictionary
+			    dictionaryWithObject: index
+					  forKey: OFNetworkInterfaceIndex];
+
+			[ret setObject: interface forKey: name];
+		}
 	} @finally {
 		if_freenameindex(nameindex);
 	}
 
 	[ret makeImmutable];

Index: tests/OFSystemInfoTests.m
==================================================================
--- tests/OFSystemInfoTests.m
+++ tests/OFSystemInfoTests.m
@@ -19,10 +19,14 @@
 
 @implementation TestsAppDelegate (OFSystemInfoTests)
 - (void)systemInfoTests
 {
 	void *pool = objc_autoreleasePoolPush();
+#ifdef OF_HAVE_SOCKETS
+	OFDictionary *networkInterfaces;
+	bool firstInterface = true;
+#endif
 
 	[OFStdOut setForegroundColor: [OFColor lime]];
 
 	[OFStdOut writeFormat: @"[OFSystemInfo] Page size: %zd\n",
 	    [OFSystemInfo pageSize]];
@@ -106,12 +110,21 @@
 	[OFStdOut writeFormat: @"[OFSystemInfo] Supports AltiVec: %d\n",
 	    [OFSystemInfo supportsAltiVec]];
 #endif
 
 #ifdef OF_HAVE_SOCKETS
-	[OFStdOut writeFormat: @"[OFSystemInfo] Network interfaces: %@\n",
-	    [[OFSystemInfo networkInterfaces] componentsJoinedByString: @", "]];
+	networkInterfaces = [OFSystemInfo networkInterfaces];
+	[OFStdOut writeString: @"[OFSystemInfo] Network interfaces: "];
+	for (OFString *name in networkInterfaces) {
+		if (!firstInterface)
+			[OFStdOut writeString: @"; "];
+
+		firstInterface = false;
+
+		[OFStdOut writeString: name];
+	}
+	[OFStdOut writeString: @"\n"];
 #endif
 
 	objc_autoreleasePoolPop(pool);
 }
 @end