diff --git a/src/coreclr/jit/optimizebools.cpp b/src/coreclr/jit/optimizebools.cpp
index 54f2b5bc4203be..61317173653735 100644
--- a/src/coreclr/jit/optimizebools.cpp
+++ b/src/coreclr/jit/optimizebools.cpp
@@ -209,6 +209,13 @@ bool OptBoolsDsc::optOptimizeBoolsCondBlock()
         if (m_c1->OperIs(GT_LCL_VAR) && m_c2->OperIs(GT_LCL_VAR) &&
             m_c1->AsLclVarCommon()->GetLclNum() == m_c2->AsLclVarCommon()->GetLclNum())
         {
+            // The folded comparisons below are signed (e.g. "c1 <= 0", "c1 >= 0"), so
+            // bail if either input has GTF_UNSIGNED.
+            if (m_testInfo1.GetTestOp()->IsUnsigned() || m_testInfo2.GetTestOp()->IsUnsigned())
+            {
+                return false;
+            }
+
             if ((m_testInfo1.compTree->OperIs(GT_LT) && m_testInfo2.compTree->OperIs(GT_EQ)) ||
                 (m_testInfo1.compTree->OperIs(GT_EQ) && m_testInfo2.compTree->OperIs(GT_LT)))
             {
@@ -271,6 +278,13 @@ bool OptBoolsDsc::optOptimizeBoolsCondBlock()
         if (m_c1->OperIs(GT_LCL_VAR) && m_c2->OperIs(GT_LCL_VAR) &&
             m_c1->AsLclVarCommon()->GetLclNum() == m_c2->AsLclVarCommon()->GetLclNum())
         {
+            // The folded comparisons below are signed (e.g. "c1 > 0", "c1 < 0"), so
+            // bail if either input has GTF_UNSIGNED.
+            if (m_testInfo1.GetTestOp()->IsUnsigned() || m_testInfo2.GetTestOp()->IsUnsigned())
+            {
+                return false;
+            }
+
             if ((m_testInfo1.compTree->OperIs(GT_LT) && m_testInfo2.compTree->OperIs(GT_NE)) ||
                 (m_testInfo1.compTree->OperIs(GT_EQ) && m_testInfo2.compTree->OperIs(GT_GE)))
             {
diff --git a/src/tests/JIT/Regression/JitBlue/Runtime_128895/Runtime_128895.cs b/src/tests/JIT/Regression/JitBlue/Runtime_128895/Runtime_128895.cs
new file mode 100644
index 00000000000000..cda3cef2a74e27
--- /dev/null
+++ b/src/tests/JIT/Regression/JitBlue/Runtime_128895/Runtime_128895.cs
@@ -0,0 +1,112 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+// optOptimizeBoolsCondBlock folded a pair of BBJ_COND blocks of the form
+// "(x == 0) || (x relop 0)" into a single directional comparison (e.g. LT/LE/GE)
+// via SetOper, which preserved gtFlags. When the EQ side was imported from
+// "beq.un"/"bne.un" (the typical C# pattern for "long == 0") it carried a
+// meaningless GTF_UNSIGNED that became semantically active on the rewritten
+// directional relop, producing "x <_U 0" (always false) or "x >=_U 0"
+// (always true) instead of the intended signed comparison.
+
+namespace Runtime_128895;
+
+using System.Runtime.CompilerServices;
+using Xunit;
+
+public abstract class Base
+{
+    public long fValue;
+    public abstract int Compare(long other);
+}
+
+public sealed class Cell : Base
+{
+    public override int Compare(long other)
+    {
+        if (fValue == other) return 0;
+        if (fValue > other) return 1;
+        return -1;
+    }
+}
+
+public static class CellPool
+{
+    private static readonly Cell[] s_pool = CreatePool();
+    private static int s_slot;
+
+    private static Cell[] CreatePool()
+    {
+        Cell[] pool = new Cell[16];
+        for (int i = 0; i < pool.Length; i++)
+        {
+            pool[i] = new Cell();
+        }
+
+        return pool;
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static Cell Make(int idx)
+    {
+        Cell c = s_pool[s_slot++ & 15];
+        c.fValue = idx >= 0 ? idx + 1 : -1;
+        return c;
+    }
+}
+
+public class Runtime_128895
+{
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static int FindCharLocal(string s, string needle) =>
+        s.IndexOfAny(needle.ToCharArray(), 0, s.Length);
+
+    [MethodImpl(MethodImplOptions.NoInlining)]
+    private static bool ValidateMarks(string s)
+    {
+        bool r = false;
+        Cell mark1 = CellPool.Make(FindCharLocal(s, "\u00ab"));
+        Cell mark2 = CellPool.Make(FindCharLocal(s, "\u00bb"));
+        Cell mark3 = CellPool.Make(FindCharLocal(s, "\u201c"));
+        if ((mark1.Compare(0) == 0 || mark1.Compare(0) > 0)
+         || (mark2.Compare(0) == 0 || mark2.Compare(0) > 0)
+         || (mark3.Compare(0) == 0 || mark3.Compare(0) > 0))
+        {
+            r = true;
+        }
+
+        return r;
+    }
+
+    private static readonly string[] s_inputs = new[]
+    {
+        "abc", "def", "ghi", "jkl", "mno", "pqr", "abc\u00abdef", "xyz"
+    };
+
+    [Fact]
+    public static int TestEntryPoint()
+    {
+        // Drive ValidateMarks through Tier0 -> Instrumented Tier0 -> Tier1+PGO.
+        for (int i = 0; i < 1000; i++)
+        {
+            ValidateMarks(s_inputs[i & 7]);
+            System.Threading.Thread.Sleep(1);
+        }
+
+        System.Threading.Thread.Sleep(100);
+
+        int failures = 0;
+        for (int k = 0; k < s_inputs.Length; k++)
+        {
+            string s = s_inputs[k];
+            bool expected = s.Contains('\u00ab') || s.Contains('\u00bb') || s.Contains('\u201c');
+            bool actual = ValidateMarks(s);
+            if (expected != actual)
+            {
+                failures++;
+            }
+        }
+
+        return failures == 0 ? 100 : 1;
+    }
+}
diff --git a/src/tests/JIT/Regression/JitBlue/Runtime_128895/Runtime_128895.csproj b/src/tests/JIT/Regression/JitBlue/Runtime_128895/Runtime_128895.csproj
new file mode 100644
index 00000000000000..09fb4358127787
--- /dev/null
+++ b/src/tests/JIT/Regression/JitBlue/Runtime_128895/Runtime_128895.csproj
@@ -0,0 +1,13 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <DebugType>None</DebugType>
+    <Optimize>True</Optimize>
+    <!-- Needed for CLRTestEnvironmentVariable -->
+    <RequiresProcessIsolation>true</RequiresProcessIsolation>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="$(MSBuildProjectName).cs" />
+    <CLRTestEnvironmentVariable Include="DOTNET_TieredCompilation" Value="1" />
+    <CLRTestEnvironmentVariable Include="DOTNET_TieredPGO" Value="1" />
+  </ItemGroup>
+</Project>