diff --git a/unittests/Format/FormatTest.cpp b/unittests/Format/FormatTest.cpp
index 32b2ff7..9735898 100644
--- a/unittests/Format/FormatTest.cpp
+++ b/unittests/Format/FormatTest.cpp
@@ -38,6 +38,7 @@
     tooling::Replacements Replace = reformat(Style, Lex, Context.Sources,
                                              Ranges,
                                              new IgnoringDiagConsumer());
+    ReplacementCount = Replace.size();
     EXPECT_TRUE(applyAllReplacements(Replace, Context.Rewrite));
     DEBUG(llvm::errs() << "\n" << Context.getRewrittenText(ID) << "\n\n");
     return Context.getRewrittenText(ID);
@@ -105,6 +106,8 @@
     verifyFormat(text);
     verifyFormat(llvm::Twine("void f() { " + text + " }").str());
   }
+
+  int ReplacementCount;
 };
 
 TEST_F(FormatTest, MessUp) {
@@ -148,6 +151,19 @@
   verifyFormat("vector< ::Type> v;");
 }
 
+TEST_F(FormatTest, OnlyGeneratesNecessaryReplacements) {
+  EXPECT_EQ("if (a) {\n"
+            "  f();\n"
+            "}", format("if(a){f();}"));
+  EXPECT_EQ(4, ReplacementCount);
+  EXPECT_EQ("if (a) {\n"
+            "  f();\n"
+            "}", format("if (a) {\n"
+                        "  f();\n"
+                        "}"));
+  EXPECT_EQ(0, ReplacementCount);
+}
+
 //===----------------------------------------------------------------------===//
 // Tests for control statements.
 //===----------------------------------------------------------------------===//