diff --git a/lib/checkunusedvar.cpp b/lib/checkunusedvar.cpp
index 53c90d95f..9287b5102 100644
--- a/lib/checkunusedvar.cpp
+++ b/lib/checkunusedvar.cpp
@@ -692,7 +692,8 @@ void CheckUnusedVar::checkFunctionVariableUsage_iterateScopes(const Scope* const
                      i->typeEndToken()->isStandardType() ||
                      isRecordTypeWithoutSideEffects(i->type()) ||
                      (Token::simpleMatch(i->typeStartToken(), "std ::") &&
-                      i->typeStartToken()->strAt(2) != "lock_guard"))
+                      i->typeStartToken()->strAt(2) != "lock_guard" &&
+                      i->typeStartToken()->strAt(2) != "unique_lock"))
                 type = Variables::standard;
             if (type == Variables::none || isPartOfClassStructUnion(i->typeStartToken()))
                 continue;
diff --git a/test/testunusedvar.cpp b/test/testunusedvar.cpp
index 24f83577c..d44d81aac 100644
--- a/test/testunusedvar.cpp
+++ b/test/testunusedvar.cpp
@@ -3537,6 +3537,12 @@ private:
                               "    std::lock_guard<MyClass> lock(mutex_);\n" // Has a side-effect #4385
                               "}");
         ASSERT_EQUALS("", errout.str());
+
+        functionVariableUsage("void f() {\n"
+                              "    std::mutex m;\n"
+                              "    std::unique_lock<std::mutex> lock(m);\n" // #4624
+                              "}");
+        ASSERT_EQUALS("", errout.str());
     }
 
     // ticket #3104 - false positive when variable is read with "if (NOT var)"