diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 2d20bc03651c7..43225304670f6 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -72,6 +72,8 @@ class FormatTest : public ::testing::Test {
 
   void verifyFormat(llvm::StringRef Expected, llvm::StringRef Code,
                     const FormatStyle &Style = getLLVMStyle()) {
+    EXPECT_EQ(Expected.str(), format(Expected, Style))
+        << "Expected code is not stable";
     EXPECT_EQ(Expected.str(), format(Code, Style));
     if (Style.Language == FormatStyle::LK_Cpp) {
       // Objective-C++ is a superset of C++, so everything checked for C++
diff --git a/clang/unittests/Format/FormatTestComments.cpp b/clang/unittests/Format/FormatTestComments.cpp
index ed11fbdb1fc0d..005039698bba4 100644
--- a/clang/unittests/Format/FormatTestComments.cpp
+++ b/clang/unittests/Format/FormatTestComments.cpp
@@ -70,6 +70,7 @@ class FormatTestComments : public ::testing::Test {
 
   void verifyFormat(llvm::StringRef Code,
                     const FormatStyle &Style = getLLVMStyle()) {
+    EXPECT_EQ(Code.str(), format(Code, Style)) << "Expected code is not stable";
     EXPECT_EQ(Code.str(), format(test::messUp(Code), Style));
   }
 
diff --git a/clang/unittests/Format/FormatTestJS.cpp b/clang/unittests/Format/FormatTestJS.cpp
index 5fb47a7d32f0b..347118353e368 100644
--- a/clang/unittests/Format/FormatTestJS.cpp
+++ b/clang/unittests/Format/FormatTestJS.cpp
@@ -49,6 +49,8 @@ class FormatTestJS : public ::testing::Test {
   static void verifyFormat(
       llvm::StringRef Code,
       const FormatStyle &Style = getGoogleStyle(FormatStyle::LK_JavaScript)) {
+    EXPECT_EQ(Code.str(), format(Code, Style))
+        << "Expected code is not stable";
     std::string Result = format(test::messUp(Code), Style);
     EXPECT_EQ(Code.str(), Result) << "Formatted:\n" << Result;
   }
@@ -57,6 +59,8 @@ class FormatTestJS : public ::testing::Test {
       llvm::StringRef Expected,
       llvm::StringRef Code,
       const FormatStyle &Style = getGoogleStyle(FormatStyle::LK_JavaScript)) {
+    EXPECT_EQ(Expected.str(), format(Expected, Style))
+        << "Expected code is not stable";
     std::string Result = format(Code, Style);
     EXPECT_EQ(Expected.str(), Result) << "Formatted:\n" << Result;
   }
diff --git a/clang/unittests/Format/FormatTestJava.cpp b/clang/unittests/Format/FormatTestJava.cpp
index 1d471b73ee64e..36b72fda475f1 100644
--- a/clang/unittests/Format/FormatTestJava.cpp
+++ b/clang/unittests/Format/FormatTestJava.cpp
@@ -46,6 +46,7 @@ class FormatTestJava : public ::testing::Test {
   static void verifyFormat(
       llvm::StringRef Code,
       const FormatStyle &Style = getGoogleStyle(FormatStyle::LK_Java)) {
+    EXPECT_EQ(Code.str(), format(Code, Style)) << "Expected code is not stable";
     EXPECT_EQ(Code.str(), format(test::messUp(Code), Style));
   }
 };
diff --git a/clang/unittests/Format/FormatTestObjC.cpp b/clang/unittests/Format/FormatTestObjC.cpp
index ed5d1aa25609b..b54b1c0b63db7 100644
--- a/clang/unittests/Format/FormatTestObjC.cpp
+++ b/clang/unittests/Format/FormatTestObjC.cpp
@@ -58,6 +58,7 @@ class FormatTestObjC : public ::testing::Test {
   }
 
   void verifyFormat(StringRef Code) {
+    EXPECT_EQ(Code.str(), format(Code)) << "Expected code is not stable";
     EXPECT_EQ(Code.str(), format(test::messUp(Code)));
   }
 
diff --git a/clang/unittests/Format/FormatTestProto.cpp b/clang/unittests/Format/FormatTestProto.cpp
index 66c5d3778d4a3..672fd5914d077 100644
--- a/clang/unittests/Format/FormatTestProto.cpp
+++ b/clang/unittests/Format/FormatTestProto.cpp
@@ -38,6 +38,7 @@ class FormatTestProto : public ::testing::Test {
   }
 
   static void verifyFormat(llvm::StringRef Code) {
+    EXPECT_EQ(Code.str(), format(Code)) << "Expected code is not stable";
     EXPECT_EQ(Code.str(), format(test::messUp(Code)));
   }
 };
diff --git a/clang/unittests/Format/FormatTestTextProto.cpp b/clang/unittests/Format/FormatTestTextProto.cpp
index f4e09cf9e27bd..2cd7fb7bdf305 100644
--- a/clang/unittests/Format/FormatTestTextProto.cpp
+++ b/clang/unittests/Format/FormatTestTextProto.cpp
@@ -36,6 +36,7 @@ class FormatTestTextProto : public ::testing::Test {
   }
 
   static void verifyFormat(llvm::StringRef Code, const FormatStyle &Style) {
+    EXPECT_EQ(Code.str(), format(Code, Style)) << "Expected code is not stable";
     EXPECT_EQ(Code.str(), format(test::messUp(Code), Style));
   }