Index: clang-tidy/readability/FunctionSizeCheck.cpp
===================================================================
--- clang-tidy/readability/FunctionSizeCheck.cpp
+++ clang-tidy/readability/FunctionSizeCheck.cpp
@@ -36,15 +36,8 @@
     case Stmt::ForStmtClass:
     case Stmt::SwitchStmtClass:
       ++Info.Branches;
-    // fallthrough
+      LLVM_FALLTHROUGH;
     case Stmt::CompoundStmtClass:
-      // If this new compound statement is located in a compound statement,
-      // which is already nested NestingThreshold levels deep, record the start
-      // location of this new compound statement
-      if (CurrentNestingLevel == Info.NestingThreshold)
-        Info.NestingThresholders.push_back(Node->getLocStart());
-
-      ++CurrentNestingLevel;
       TrackedParent.push_back(true);
       break;
     default:
@@ -54,13 +47,25 @@
 
     Base::TraverseStmt(Node);
 
-    if (TrackedParent.back())
-      --CurrentNestingLevel;
     TrackedParent.pop_back();
 
     return true;
   }
 
+  bool TraverseCompoundStmt(CompoundStmt *Node) {
+    // If this new compound statement is located in a compound statement, which
+    // is already nested NestingThreshold levels deep, record the start location
+    // of this new compound statement
+    if (CurrentNestingLevel == Info.NestingThreshold)
+      Info.NestingThresholders.push_back(Node->getLocStart());
+
+    ++CurrentNestingLevel;
+    Base::TraverseCompoundStmt(Node);
+    --CurrentNestingLevel;
+
+    return true;
+  }
+
   bool TraverseDecl(Decl *Node) {
     TrackedParent.push_back(false);
     Base::TraverseDecl(Node);
Index: test/clang-tidy/readability-function-size.cpp
===================================================================
--- test/clang-tidy/readability-function-size.cpp
+++ test/clang-tidy/readability-function-size.cpp
@@ -63,8 +63,9 @@
 #define macro() {int x; {int y; {int z;}}}
 
 void baz0() { // 1
-// CHECK-MESSAGES: :[[@LINE-1]]:6: warning: function 'baz0' exceeds recommended size/complexity
-// CHECK-MESSAGES: :[[@LINE-2]]:6: note: 9 statements (threshold 0)
+  // CHECK-MESSAGES: :[[@LINE-1]]:6: warning: function 'baz0' exceeds recommended size/complexity
+  // CHECK-MESSAGES: :[[@LINE-2]]:6: note: 27 lines including whitespace and comments (threshold 0)
+  // CHECK-MESSAGES: :[[@LINE-3]]:6: note: 9 statements (threshold 0)
   int a;
   { // 2
     int b;
@@ -87,5 +88,55 @@
   }
   macro()
 // CHECK-MESSAGES: :[[@LINE-1]]:3: note: nesting level 3 starts here (threshold 2)
-// CHECK-MESSAGES: :[[@LINE-27]]:25: note: expanded from macro 'macro'
+// CHECK-MESSAGES: :[[@LINE-28]]:25: note: expanded from macro 'macro'
+}
+
+// check that nested if's are not reported. this was broken initially
+void nesting_if() { // 1
+  // CHECK-MESSAGES: :[[@LINE-1]]:6: warning: function 'nesting_if' exceeds recommended size/complexity
+  // CHECK-MESSAGES: :[[@LINE-2]]:6: note: 22 lines including whitespace and comments (threshold 0)
+  // CHECK-MESSAGES: :[[@LINE-3]]:6: note: 18 statements (threshold 0)
+  // CHECK-MESSAGES: :[[@LINE-4]]:6: note: 6 branches (threshold 0)
+  if (true) { // 2
+     int j;
+  } else if (true) { // 2
+     int j;
+     if (true) { // 3
+       // CHECK-MESSAGES: :[[@LINE-1]]:16: note: nesting level 3 starts here (threshold 2)
+       int j;
+     }
+  } else if (true) { // 2
+     int j;
+     if (true) { // 3
+       // CHECK-MESSAGES: :[[@LINE-1]]:16: note: nesting level 3 starts here (threshold 2)
+       int j;
+     }
+  } else if (true) { // 2
+     int j;
+  }
+}
+
+// however this should warn
+void bad_if_nesting() { // 1
+// CHECK-MESSAGES: :[[@LINE-1]]:6: warning: function 'bad_if_nesting' exceeds recommended size/complexity
+// CHECK-MESSAGES: :[[@LINE-2]]:6: note: 22 lines including whitespace and comments (threshold 0)
+// CHECK-MESSAGES: :[[@LINE-3]]:6: note: 12 statements (threshold 0)
+// CHECK-MESSAGES: :[[@LINE-4]]:6: note: 4 branches (threshold 0)
+  if (true) {    // 2
+    int j;
+  } else { // 2
+    if (true) { // 3
+      // CHECK-MESSAGES: :[[@LINE-1]]:15: note: nesting level 3 starts here (threshold 2)
+      int j;
+    } else { // 3
+      // CHECK-MESSAGES: :[[@LINE-1]]:12: note: nesting level 3 starts here (threshold 2)
+      if (true) { // 4
+        int j;
+      } else { // 4
+        if (true) { // 5
+          int j;
+        }
+      }
+    }
+  }
 }