diff --git a/lib/forwardanalyzer.cpp b/lib/forwardanalyzer.cpp
index 6590f0ebd..a3dd51111 100644
--- a/lib/forwardanalyzer.cpp
+++ b/lib/forwardanalyzer.cpp
@@ -209,6 +209,7 @@ struct ForwardTraversal {
     }
 
     Progress updateLoop(Token* endBlock, Token* condTok, Token* initTok = nullptr, Token* stepTok = nullptr) {
+        const bool isDoWhile = precedes(endBlock, condTok);
         ForwardAnalyzer::Action bodyAnalysis = analyzeScope(endBlock);
         ForwardAnalyzer::Action allAnalysis = bodyAnalysis;
         if (condTok)
@@ -225,7 +226,7 @@ struct ForwardTraversal {
                 return Progress::Break;
         }
         // Traverse condition after lowering
-        if (condTok) {
+        if (condTok && (!isDoWhile || !bodyAnalysis.isModified())) {
             if (updateRecursive(condTok) == Progress::Break)
                 return Progress::Break;
 
diff --git a/test/testuninitvar.cpp b/test/testuninitvar.cpp
index 6cda95d44..36f24fc74 100644
--- a/test/testuninitvar.cpp
+++ b/test/testuninitvar.cpp
@@ -4430,6 +4430,16 @@ private:
                         "        f += 1;\n"
                         "}\n");
         ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("unsigned char get();\n"
+                        "char f() {\n"
+                        "    unsigned char c;\n"
+                        "    do {\n"
+                        "        c = get();\n"
+                        "    } while (isalpha(c) == 0);\n"
+                        "    return static_cast<char>(c);\n"
+                        "}\n");
+        ASSERT_EQUALS("", errout.str());
     }
 
     void uninitvar_ipa() {