diff --git a/lib/checkbufferoverrun.cpp b/lib/checkbufferoverrun.cpp
index 7a1d226af..3c7380f29 100644
--- a/lib/checkbufferoverrun.cpp
+++ b/lib/checkbufferoverrun.cpp
@@ -1089,7 +1089,7 @@ void CheckBufferOverrun::checkGlobalAndLocalVariable()
                 if (!it->tokvalue)
                     continue;
                 const Variable *var = it->tokvalue->variable();
-                if (var && var->isArray() && var->dimensions().size() == 1U && value->intvalue > var->dimension(0)) {
+                if (var && var->isArray() && var->dimensions().size() == 1U && var->dimensionKnown(0) && value->intvalue > var->dimension(0)) {
                     std::list<const Token *> callstack;
                     callstack.push_back(it->tokvalue);
                     callstack.push_back(tok);
diff --git a/test/testbufferoverrun.cpp b/test/testbufferoverrun.cpp
index 86fc4e937..7bff56ca0 100644
--- a/test/testbufferoverrun.cpp
+++ b/test/testbufferoverrun.cpp
@@ -2065,6 +2065,13 @@ private:
               "  p[20] = 0;\n"
               "}");
         ASSERT_EQUALS("[test.cpp:3] -> [test.cpp:4]: (error) Array 'a[10]' accessed at index 20, which is out of bounds.\n", errout.str());
+
+        check("void f() {\n"
+              "  int a[X];\n"
+              "  int *p = a;\n"
+              "  p[20] = 0;\n"
+              "}");
+        ASSERT_EQUALS("", errout.str());
     }
 
     void array_index_function_parameter() {