Index: clang/test/Format/line-ranges.cpp
===================================================================
--- clang/test/Format/line-ranges.cpp
+++ clang/test/Format/line-ranges.cpp
@@ -9,3 +9,11 @@
 
 // CHECK: {{^int\ \*i;$}}
 int   *   i;
+
+// RUN: not clang-format -lines=0:1 < %s 2>&1 \
+// RUN:   | FileCheck -strict-whitespace -check-prefix=CHECK0 %s
+// CHECK0: error: start line should be at least 1
+
+// RUN: not clang-format -lines=2:1 < %s 2>&1 \
+// RUN:   | FileCheck -strict-whitespace -check-prefix=CHECK1 %s
+// CHECK1: error: start line should not exceed end line
Index: clang/tools/clang-format/ClangFormat.cpp
===================================================================
--- clang/tools/clang-format/ClangFormat.cpp
+++ clang/tools/clang-format/ClangFormat.cpp
@@ -246,8 +246,12 @@
         errs() << "error: invalid <start line>:<end line> pair\n";
         return true;
       }
+      if (FromLine < 1) {
+        errs() << "error: start line should be at least 1\n";
+        return true;
+      }
       if (FromLine > ToLine) {
-        errs() << "error: start line should be less than end line\n";
+        errs() << "error: start line should not exceed end line\n";
         return true;
       }
       SourceLocation Start = Sources.translateLineCol(ID, FromLine, 1);