diff --git a/lib/vf_analyzers.cpp b/lib/vf_analyzers.cpp
index 27c27934f31..b3e692be891 100644
--- a/lib/vf_analyzers.cpp
+++ b/lib/vf_analyzers.cpp
@@ -228,7 +228,8 @@ struct ValueFlowAnalyzer : Analyzer {
         if (inconclusive)
             return Action::Read | Action::Inconclusive;
         if (isVariableChanged(tok, getIndirect(tok), getSettings())) {
-            if (Token::Match(tok->astParent(), "*|[|.|++|--"))
+            if (Token::Match(tok->astParent(), "*|[|.|++|--") ||
+                (Token::Match(tok->astParent(), "%assign%") && tok->astParent()->str().size() > 1)) // compound assignment
                 return Action::Read | Action::Invalid;
             // Check if its assigned to the same value
             if (value && !value->isImpossible() && Token::simpleMatch(tok->astParent(), "=") && astIsLHS(tok) &&
diff --git a/test/testnullpointer.cpp b/test/testnullpointer.cpp
index ca5c183c911..111e04c35f6 100644
--- a/test/testnullpointer.cpp
+++ b/test/testnullpointer.cpp
@@ -4707,7 +4707,7 @@ class TestNullPointer : public TestFixture {
               "    p += a;\n"
               "    *p = 0;\n"
               "}\n");
-        ASSERT_EQUALS("", errout_str());
+        ASSERT_EQUALS("[test.cpp:2:7]: (error) Pointer addition with NULL pointer. [nullPointerArithmetic]\n", errout_str());
 
         check("int f(int *p = 0) {\n"
               "    if (p == 0) {\n"
diff --git a/test/testuninitvar.cpp b/test/testuninitvar.cpp
index 4d1a913ed3a..31581ce62a2 100644
--- a/test/testuninitvar.cpp
+++ b/test/testuninitvar.cpp
@@ -6846,6 +6846,15 @@ class TestUninitVar : public TestFixture {
                         "    return a[0];\n"
                         "}\n");
         ASSERT_EQUALS("", errout_str());
+
+        valueFlowUninit("void f(int i) {\n"
+                        "    int x, y;\n"
+                        "    x += i;\n"
+                        "    y <<= i;\n"
+                        "}\n");
+        ASSERT_EQUALS("[test.cpp:3:5]: (error) Uninitialized variable: x [uninitvar]\n"
+                      "[test.cpp:4:5]: (error) Uninitialized variable: y [uninitvar]\n",
+                      errout_str());
     }
 
     void valueFlowUninitBreak() { // Do not show duplicate warnings about the same uninitialized value
diff --git a/test/testvalueflow.cpp b/test/testvalueflow.cpp
index 3609bf2aee2..7ec73a4868f 100644
--- a/test/testvalueflow.cpp
+++ b/test/testvalueflow.cpp
@@ -1110,6 +1110,22 @@ class TestValueFlow : public TestFixture {
                "    g(std::move(x)).f(1);\n"
                "}\n";
         ASSERT_EQUALS(false, testValueOfX(code, 5U, ValueFlow::Value::MoveKind::MovedVariable));
+
+        code = "void f(std::string x) {\n" // #15155
+               "    std::string a{ std::move(x) };\n"
+               "    x += \"abc\";\n"
+               "}\n";
+        ASSERT_EQUALS(true, testValueOfX(code, 3U, ValueFlow::Value::MoveKind::MovedVariable));
+
+        code = "struct S {\n"
+               "    S& operator<<=(int i);\n"
+               "    std::string m;\n"
+               "};\n"
+               "void f(S x) {\n"
+               "    S a{ std::move(x) };\n"
+               "    x <<= 5;\n"
+               "}";
+        ASSERT_EQUALS(true, testValueOfX(code, 7U, ValueFlow::Value::MoveKind::MovedVariable));
     }
 
     void valueFlowCalculations() {