diff --git a/Sources/NetworkCityCore/IPRanges.swift b/Sources/NetworkCityCore/IPRanges.swift
index 2347eba..f79fd9d 100644
--- a/Sources/NetworkCityCore/IPRanges.swift
+++ b/Sources/NetworkCityCore/IPRanges.swift
@@ -13,6 +13,16 @@ public enum IPRanges {
         ("149.154.160.0/20",  "telegram",   "Telegram"),
         ("91.108.0.0/16",     "telegram",   "Telegram"),
         ("13.64.0.0/11",      "microsoft",  "Microsoft"),
+        // Microsoft 365 / OneDrive front-ends — no PTR, so without these each
+        // IP fragments into its own district. These are Microsoft-operated
+        // service ranges (not generic Azure tenant space, which would wrongly
+        // relabel third-party apps hosted on Azure).
+        ("13.104.0.0/14",     "microsoft",  "Microsoft"),   // incl. 13.107.x
+        ("150.171.0.0/16",    "microsoft",  "Microsoft"),
+        ("52.108.0.0/14",     "microsoft",  "Microsoft"),   // O365 common
+        ("52.112.0.0/14",     "microsoft",  "Microsoft"),   // Teams/Skype
+        ("40.96.0.0/13",      "microsoft",  "Microsoft"),   // Exchange Online
+        ("40.104.0.0/15",     "microsoft",  "Microsoft"),
         ("157.240.0.0/16",    "meta",       "Meta"),
         ("31.13.24.0/21",     "meta",       "Meta"),
         ("129.134.0.0/16",    "meta",       "Meta"),
diff --git a/Tests/NetworkCityCoreTests/IPRangesTests.swift b/Tests/NetworkCityCoreTests/IPRangesTests.swift
index 955e1d7..938b3ae 100644
--- a/Tests/NetworkCityCoreTests/IPRangesTests.swift
+++ b/Tests/NetworkCityCoreTests/IPRangesTests.swift
@@ -12,6 +12,14 @@ final class IPRangesTests: XCTestCase {
         XCTAssertEqual(IPRanges.match("149.154.175.54")?.key, "telegram")
     }
 
+    func testOneDriveNoPTRRangesCollapseToMicrosoft() {
+        // Real OneDrive front-end IPs (no PTR) that used to fragment per-IP.
+        XCTAssertEqual(IPRanges.match("13.107.137.11")?.key, "microsoft")
+        XCTAssertEqual(IPRanges.match("150.171.22.11")?.name, "Microsoft")
+        XCTAssertEqual(IPRanges.match("52.108.1.1")?.key, "microsoft")
+        XCTAssertEqual(IPRanges.match("40.96.0.1")?.key, "microsoft")
+    }
+
     func testPrivateRangesAreLocalNetwork() {
         XCTAssertEqual(IPRanges.match("192.168.0.1")?.name, "Local Network")
         XCTAssertEqual(IPRanges.match("10.1.2.3")?.key, "lan")