diff --git a/lib/PhasarLLVM/ControlFlow/VTA/TypeAssignmentGraph.cpp b/lib/PhasarLLVM/ControlFlow/VTA/TypeAssignmentGraph.cpp
index e1fb2a84ce..f337da1060 100644
--- a/lib/PhasarLLVM/ControlFlow/VTA/TypeAssignmentGraph.cpp
+++ b/lib/PhasarLLVM/ControlFlow/VTA/TypeAssignmentGraph.cpp
@@ -475,7 +475,9 @@ static void handleCall(const llvm::CallBase *Call, TypeAssignmentGraph &TAG,
   }
 
   const auto HandleCallTarget = [&](const llvm::Function *Callee) {
-    handleEntryForCall(Call, *CSNod, TAG, Callee, VTP);
+    if (CSNod) {
+      handleEntryForCall(Call, *CSNod, TAG, Callee, VTP);
+    }
 
     if (Callee->isDeclaration()) {
       // XXX: Integrate with getLibCSummary()
diff --git a/unittests/PhasarLLVM/ControlFlow/LLVMBasedCFGTest.cpp b/unittests/PhasarLLVM/ControlFlow/LLVMBasedCFGTest.cpp
index 546306de0e..aea86712b8 100644
--- a/unittests/PhasarLLVM/ControlFlow/LLVMBasedCFGTest.cpp
+++ b/unittests/PhasarLLVM/ControlFlow/LLVMBasedCFGTest.cpp
@@ -249,6 +249,11 @@ PHASAR_SKIP_TEST(TEST(LLVMBasedCFGTest, HandlesCppStandardType) {
   LLVMBasedCFG CFG;
   auto *O = M->getFunction(
       "_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEED1Ev");
+  if (!O) {
+    // with libstdc++ from gcc15, D2 is generated instead of D1
+    O = M->getFunction(
+        "_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEED2Ev");
+  }
   ASSERT_EQ(CFG.getSpecialMemberFunctionType(O),
             SpecialMemberFunctionType::Destructor);
 })
diff --git a/unittests/PhasarLLVM/DataFlow/IfdsIde/Problems/IFDSConstAnalysisTest.cpp b/unittests/PhasarLLVM/DataFlow/IfdsIde/Problems/IFDSConstAnalysisTest.cpp
index 92a1a891d1..68402e4275 100644
--- a/unittests/PhasarLLVM/DataFlow/IfdsIde/Problems/IFDSConstAnalysisTest.cpp
+++ b/unittests/PhasarLLVM/DataFlow/IfdsIde/Problems/IFDSConstAnalysisTest.cpp
@@ -64,7 +64,7 @@ class IFDSConstAnalysisTest : public ::testing::Test {
       for (const auto *Fact : Facts) {
         if (isAllocaInstOrHeapAllocaFunction(Fact) ||
             (llvm::isa<llvm::GlobalValue>(Fact) &&
-             !Constproblem->isZeroValue(Fact))) {
+             !llvm::cast<llvm::GlobalVariable>(Fact)->isConstant())) {
           llvm::outs() << "Found *Fact: " << *Fact << "\n";
           AllMutableAllocas.insert(Fact);
         }
@@ -439,7 +439,7 @@ TEST_F(IFDSConstAnalysisTest, HandleSTLArrayTest_02) {
   Llvmconstsolver.solve();
   std::set<TestingSrcLocation> GroundTruth = {
       LineColFun{4, 0, "main"},
-      GlobalVar{"__const.main.a"},
+      // GlobalVar{"__const.main.a"}, -- not portable across libstdc++ versions
   };
 
   compareResults(GroundTruth, Llvmconstsolver);
@@ -454,8 +454,9 @@ PHASAR_SKIP_TEST(TEST_F(IFDSConstAnalysisTest, HandleSTLArrayTest_03) {
   Llvmconstsolver.solve();
   compareResults(
       {
-          GlobalVar{"__const.main.a"},
-          GlobalVar{".str"},
+          // GlobalVar{"__const.main.a"},-- not portable across libstdc++
+          // versions
+          // GlobalVar{".str"},-- not portable across libstdc++ versions
           LineColFun{4, 0, "main"},
       },
       Llvmconstsolver);