diff --git a/lib/checkother.cpp b/lib/checkother.cpp
index 709031847..b3da83ec7 100644
--- a/lib/checkother.cpp
+++ b/lib/checkother.cpp
@@ -42,6 +42,7 @@
 #include <set>
 #include <type_traits>
 #include <utility>
+#include <numeric>
 
 //---------------------------------------------------------------------------
 
@@ -1155,6 +1156,13 @@ static int estimateSize(const Type* type, const Settings* settings, const Symbol
         return 0;
 
     int cumulatedSize = 0;
+    const bool isUnion = type->classScope->type == Scope::ScopeType::eUnion;
+    const auto accumulateSize = [](int& cumulatedSize, int size, bool isUnion) -> void {
+        if (isUnion)
+            cumulatedSize = std::max(cumulatedSize, size);
+        else
+            cumulatedSize += size;
+    };
     for (const Variable&var : type->classScope->varlist) {
         int size = 0;
         if (var.isStatic())
@@ -1169,9 +1177,11 @@ static int estimateSize(const Type* type, const Settings* settings, const Symbol
             size = symbolDatabase->sizeOfType(var.typeStartToken());
 
         if (var.isArray())
-            cumulatedSize += size * var.dimension(0);
-        else
-            cumulatedSize += size;
+            size *= std::accumulate(var.dimensions().begin(), var.dimensions().end(), 1, [](int v, const Dimension& d) {
+                return v *= d.num;
+            });
+
+        accumulateSize(cumulatedSize, size, isUnion);
     }
     for (const Type::BaseInfo &baseInfo : type->derivedFrom) {
         if (baseInfo.type && baseInfo.type->classScope)
diff --git a/test/testother.cpp b/test/testother.cpp
index 01ef808cc..5badbe7aa 100644
--- a/test/testother.cpp
+++ b/test/testother.cpp
@@ -1665,6 +1665,18 @@ private:
               "void foo(X x4){}\n");
         ASSERT_EQUALS("", errout.str());
 
+        check("union U {\n"
+              "    char* pc;\n"
+              "    short* ps;\n"
+              "    int* pi;\n"
+              "};\n"
+              "void f(U u) {}\n");
+        ASSERT_EQUALS("", errout.str());
+
+        check("struct S { char A[8][8]; };\n"
+              "void f(S s) {}\n");
+        ASSERT_EQUALS("[test.cpp:2]: (performance) Function parameter 's' should be passed by const reference.\n", errout.str());
+
         Settings settings1;
         settings1.platform(Settings::Win64);
         check("using ui64 = unsigned __int64;\n"