Index: clang/lib/StaticAnalyzer/Checkers/IteratorChecker.cpp
===================================================================
--- clang/lib/StaticAnalyzer/Checkers/IteratorChecker.cpp
+++ clang/lib/StaticAnalyzer/Checkers/IteratorChecker.cpp
@@ -180,7 +180,7 @@
   std::unique_ptr<BugType> InvalidatedBugType;
   std::unique_ptr<BugType> DebugMsgBugType;
 
-  void handleComparison(CheckerContext &C, const Expr *CE, const SVal &RetVal,
+  void handleComparison(CheckerContext &C, const Expr *CE, SVal RetVal,
                         const SVal &LVal, const SVal &RVal,
                         OverloadedOperatorKind Op) const;
   void processComparison(CheckerContext &C, ProgramStateRef State,
@@ -883,7 +883,7 @@
 }
 
 void IteratorChecker::handleComparison(CheckerContext &C, const Expr *CE,
-                                       const SVal &RetVal, const SVal &LVal,
+                                       SVal RetVal, const SVal &LVal,
                                        const SVal &RVal,
                                        OverloadedOperatorKind Op) const {
   // Record the operands and the operator of the comparison for the next
@@ -922,6 +922,16 @@
     RPos = getIteratorPosition(State, RVal);
   }
 
+  // We cannot make assumpotions on `UnknownVal`. Let us conjure a symbol
+  // instead.
+  if (RetVal.isUnknown()) {
+    auto &SymMgr = C.getSymbolManager();
+    auto *LCtx = C.getLocationContext();
+    RetVal = nonloc::SymbolVal(SymMgr.conjureSymbol(
+        CE, LCtx, C.getASTContext().BoolTy, C.blockCount()));
+    State = State->BindExpr(CE, LCtx, RetVal);
+  }
+
   processComparison(C, State, LPos->getOffset(), RPos->getOffset(), RetVal, Op);
 }
 
@@ -943,7 +953,7 @@
   const auto ConditionVal = RetVal.getAs<DefinedSVal>();
   if (!ConditionVal)
     return;
-  
+
   if (auto StateTrue = relateSymbols(State, Sym1, Sym2, Op == OO_EqualEqual)) {
     StateTrue = StateTrue->assume(*ConditionVal, true);
     C.addTransition(StateTrue);
Index: clang/test/Analysis/invalidated-iterator.cpp
===================================================================
--- clang/test/Analysis/invalidated-iterator.cpp
+++ clang/test/Analysis/invalidated-iterator.cpp
@@ -120,4 +120,3 @@
   V.erase(i);
   auto j = V.cbegin(); // no-warning
 }
-
Index: clang/test/Analysis/iterator-modelling.cpp
===================================================================
--- clang/test/Analysis/iterator-modelling.cpp
+++ clang/test/Analysis/iterator-modelling.cpp
@@ -1966,7 +1966,7 @@
   clang_analyzer_eval(clang_analyzer_container_end(V) ==
                       clang_analyzer_iterator_position(first)); // expected-warning@-1{{FALSE}} expected-warning@-1{{TRUE}}
   if (V.end() != first) {
-      clang_analyzer_eval(clang_analyzer_container_end(V) ==
-                        clang_analyzer_iterator_position(first)); // expected-warning@-1{{FALSE}} expected-warning@-1 0-1{{TRUE}} FIXME: should only expect FALSE in every case
+    clang_analyzer_eval(clang_analyzer_container_end(V) ==
+                        clang_analyzer_iterator_position(first)); // expected-warning@-1{{FALSE}}
   }
 }