diff --git a/lib/checkbufferoverrun.cpp b/lib/checkbufferoverrun.cpp
index 36254bded..527d2763e 100644
--- a/lib/checkbufferoverrun.cpp
+++ b/lib/checkbufferoverrun.cpp
@@ -1043,6 +1043,14 @@ void CheckBufferOverrun::checkScope(const Token *tok, const ArrayInfo &arrayInfo
             --indentlevel;
         }
 
+        // Skip array declarations
+        else if (Token::Match(tok, "[;{}] %type% *| %var% [") &&
+                 tok->strAt(1) != "return")
+        {
+            tok = tok->tokAt(3);
+            continue;
+        }
+
         else if (Token::Match(tok, "%varid% [ %num% ]", arrayInfo.varid))
         {
             std::vector<MathLib::bigint> indexes;
diff --git a/test/testbufferoverrun.cpp b/test/testbufferoverrun.cpp
index c29801952..438198b3a 100644
--- a/test/testbufferoverrun.cpp
+++ b/test/testbufferoverrun.cpp
@@ -117,6 +117,7 @@ private:
         TEST_CASE(array_index_for);        // FN: for,if
         TEST_CASE(array_index_for_neq);    // #2211: Using != in condition
         TEST_CASE(array_index_for_question);	// #2561: for, ?:
+        TEST_CASE(array_index_extern);      // FP when using 'extern'. #1684
 
         TEST_CASE(buffer_overrun_1);
         TEST_CASE(buffer_overrun_2);
@@ -1381,6 +1382,14 @@ private:
         ASSERT_EQUALS("", errout.str());
     }
 
+    void array_index_extern()
+    {
+        // Ticket #1684. FP when using 'extern'.
+        check("extern char arr[15];\n"
+              "char arr[15] = \"abc\";");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void buffer_overrun_1()
     {
         check("void f()\n"