diff --git a/lib/programmemory.cpp b/lib/programmemory.cpp
index 9bbd46aea5b..86d5e35273d 100644
--- a/lib/programmemory.cpp
+++ b/lib/programmemory.cpp
@@ -45,7 +45,12 @@
 #include <utility>
 #include <vector>
 
-ExprIdToken::ExprIdToken(const Token* tok) : tok(tok), exprid(tok ? tok->exprId() : 0) {}
+ExprIdToken::ExprIdToken(const Token* tok)
+    : tok(tok)
+{
+    assert(tok);
+    exprid = tok->exprId();
+}
 
 ExprIdToken::ExprIdToken(nonneg int exprId) : exprid(exprId) {}
 
@@ -59,6 +64,9 @@ std::size_t ExprIdToken::Hash::operator()(ExprIdToken etok) const
 }
 
 void ProgramMemory::setValue(const Token* expr, const ValueFlow::Value& value) {
+    if (!expr)
+        return;
+
     copyOnWrite();
 
     ValueFlow::Value subvalue = value;
diff --git a/lib/valueflow.cpp b/lib/valueflow.cpp
index 1d9b7f98d64..049e953f59f 100644
--- a/lib/valueflow.cpp
+++ b/lib/valueflow.cpp
@@ -6321,6 +6321,8 @@ const Token* ValueFlow::solveExprValue(const Token* expr,
                                        const std::function<std::vector<MathLib::bigint>(const Token*)>& eval,
                                        ValueFlow::Value& value)
 {
+    if (!expr)
+        return nullptr;
     if (!value.isIntValue() && !value.isIteratorValue() && !value.isSymbolicValue())
         return expr;
     if (value.isSymbolicValue() && !Token::Match(expr, "+|-"))
diff --git a/lib/vf_analyzers.cpp b/lib/vf_analyzers.cpp
index 54aeeab3034..294ae8a1d5e 100644
--- a/lib/vf_analyzers.cpp
+++ b/lib/vf_analyzers.cpp
@@ -941,8 +941,11 @@ struct MultiValueFlowAnalyzer : ValueFlowAnalyzer {
     MultiValueFlowAnalyzer(const std::unordered_map<const Variable*, ValueFlow::Value>& args, const Settings& set)
         : ValueFlowAnalyzer(set) {
         for (const auto& p:args) {
-            values[p.first->declarationId()] = p.second;
-            vars[p.first->declarationId()] = p.first;
+            const auto declId = p.first->declarationId();
+            if (declId == 0)
+                continue; // TODO: should never happen?
+            values[declId] = p.second;
+            vars[declId] = p.first;
         }
     }
 
@@ -1075,6 +1078,7 @@ struct MultiValueFlowAnalyzer : ValueFlowAnalyzer {
             const Variable* var = vars.at(p.first);
             if (!var)
                 continue;
+            assert(var->nameToken());
             ps[var->nameToken()] = p.second;
         }
         return ps;