diff --git a/FsLangMcp.fsproj b/FsLangMcp.fsproj
index 0edbf79..6f32564 100644
--- a/FsLangMcp.fsproj
+++ b/FsLangMcp.fsproj
@@ -85,7 +85,7 @@
          MSBuild that Ionide.ProjInfo loads (project load fails with MethodNotFound).
          Nerdbank.MessagePack 1.1.62 masked it by pulling 18.4.0 transitively; 1.2.30 drops
          that dependency, so pin 18.4.0 explicitly to keep project loading working. -->
-    <PackageReference Include="Microsoft.NET.StringTools" Version="[18.9.6]" />
+    <PackageReference Include="Microsoft.NET.StringTools" Version="[18.11.0]" />
     <!-- Pin the transitive load so the bind is satisfied at startup probing
          rather than first-use of StreamJsonRpc internals. Without this pin,
          fresh fslangmcp host processes (e.g. those spawned by Claude Code
diff --git a/packages.lock.json b/packages.lock.json
index d798e2c..e892144 100644
--- a/packages.lock.json
+++ b/packages.lock.json
@@ -84,9 +84,9 @@
       },
       "Microsoft.NET.StringTools": {
         "type": "Direct",
-        "requested": "[18.9.6, 18.9.6]",
-        "resolved": "18.9.6",
-        "contentHash": "CNZfh4P65tHm1Wh/uuIbYfvHlPnb0dJ9SCaIZbXRzOMn+8JEorSqSdXdGRsrDbKBDJfNG6nmgleYhnfL2pd1oQ=="
+        "requested": "[18.11.0, 18.11.0]",
+        "resolved": "18.11.0",
+        "contentHash": "46dxu08YSKeHQXbBlz/HYfVnSMJnfF1nM4v3tmfHVqIdBaz5eF8GrxWz6nl8mM3fGHZIOcp/Pr8I2zZCdb6CLA=="
       },
       "Microsoft.VisualStudio.Threading.Only": {
         "type": "Direct",
diff --git a/tests/FsLangMcp.Tests/FsLangMcp.Tests.fsproj b/tests/FsLangMcp.Tests/FsLangMcp.Tests.fsproj
index d3db81f..5e897af 100644
--- a/tests/FsLangMcp.Tests/FsLangMcp.Tests.fsproj
+++ b/tests/FsLangMcp.Tests/FsLangMcp.Tests.fsproj
@@ -85,7 +85,7 @@
     <PackageReference Include="StreamJsonRpc" Version="[2.26.150]" />
     <!-- Pin StringTools to 18.4.0; see FsLangMcp.fsproj for rationale
          (MessagePack's transitive 17.6.3 breaks Ionide.ProjInfo project loading). -->
-    <PackageReference Include="Microsoft.NET.StringTools" Version="[18.9.6]" />
+    <PackageReference Include="Microsoft.NET.StringTools" Version="[18.11.0]" />
     <PackageReference Include="xunit" Version="[2.9.3]" />
     <PackageReference Include="xunit.runner.visualstudio" Version="[4.0.0]">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
diff --git a/tests/FsLangMcp.Tests/packages.lock.json b/tests/FsLangMcp.Tests/packages.lock.json
index 9b037cc..b6a6663 100644
--- a/tests/FsLangMcp.Tests/packages.lock.json
+++ b/tests/FsLangMcp.Tests/packages.lock.json
@@ -79,9 +79,9 @@
       },
       "Microsoft.NET.StringTools": {
         "type": "Direct",
-        "requested": "[18.9.6, 18.9.6]",
-        "resolved": "18.9.6",
-        "contentHash": "CNZfh4P65tHm1Wh/uuIbYfvHlPnb0dJ9SCaIZbXRzOMn+8JEorSqSdXdGRsrDbKBDJfNG6nmgleYhnfL2pd1oQ=="
+        "requested": "[18.11.0, 18.11.0]",
+        "resolved": "18.11.0",
+        "contentHash": "46dxu08YSKeHQXbBlz/HYfVnSMJnfF1nM4v3tmfHVqIdBaz5eF8GrxWz6nl8mM3fGHZIOcp/Pr8I2zZCdb6CLA=="
       },
       "Microsoft.NET.Test.Sdk": {
         "type": "Direct",
@@ -701,7 +701,7 @@
           "FsMcp.Server": "[2.0.0, 2.0.0]",
           "FsMcp.TaskApi": "[2.0.0, 2.0.0]",
           "Ionide.ProjInfo.FCS": "[0.74.2, 0.74.2]",
-          "Microsoft.NET.StringTools": "[18.9.6, 18.9.6]",
+          "Microsoft.NET.StringTools": "[18.11.0, 18.11.0]",
           "Microsoft.VisualStudio.Threading.Only": "[18.7.23, 18.7.23]",
           "Nerdbank.MessagePack": "[1.3.88, 1.3.88]",
           "StreamJsonRpc": "[2.26.150, 2.26.150]"