diff --git a/lib/programmemory.cpp b/lib/programmemory.cpp
index 924775baf..6d2f565f3 100644
--- a/lib/programmemory.cpp
+++ b/lib/programmemory.cpp
@@ -640,13 +640,13 @@ static ValueFlow::Value execute(const Token* expr, ProgramMemory& pm)
             if (rhs.isIntValue()) {
                 std::vector<ValueFlow::Value> result =
                     infer(makeIntegralInferModel(), expr->str(), expr->astOperand1()->values(), {rhs});
-                if (result.empty())
+                if (result.empty() || !result.front().isKnown())
                     return unknown;
                 return result.front();
             } else if (lhs.isIntValue()) {
                 std::vector<ValueFlow::Value> result =
                     infer(makeIntegralInferModel(), expr->str(), {lhs}, expr->astOperand2()->values());
-                if (result.empty())
+                if (result.empty() || !result.front().isKnown())
                     return unknown;
                 return result.front();
             }
diff --git a/test/teststl.cpp b/test/teststl.cpp
index c3f922029..f489ea76d 100644
--- a/test/teststl.cpp
+++ b/test/teststl.cpp
@@ -2472,7 +2472,7 @@ private:
         check("void func(std::list<std::string> strlist) {\n"
               "    for (std::list<std::string>::iterator str = strlist.begin(); str != strlist.end(); str++) {\n"
               "        if (func2(*str)) {\n"
-              "    	       strlist.erase(str);\n"
+              "            strlist.erase(str);\n"
               "            if (strlist.empty())\n"
               "                 return;\n"
               "        }\n"
@@ -5387,6 +5387,18 @@ private:
               "}\n",
               true);
         ASSERT_EQUALS("", errout.str());
+
+        check("void f(const std::vector<int>& v, int e) {\n"
+              " if (!v.empty()) {\n"
+              "     if (e < 0 || true) {\n"
+              "         if (e < 0)\n"
+              "             return;\n"
+              "     }\n"
+              " }\n"
+              " for (auto i : v) {}\n"
+              "}\n",
+              true);
+        ASSERT_EQUALS("", errout.str());
     }
 
     void checkMutexes() {