1 files changed, 2 insertions, 1 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/Lexer.java b/src/main/java/com/google/devtools/build/lib/syntax/Lexer.java
index 15283f8a71..e5805f5bc0 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/Lexer.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/Lexer.java
@@ -252,7 +252,8 @@ public final class Lexer {
       } else if (c == '\r') {
         pos++;
       } else if (c == '\t') {
-        indentLen += 8 - indentLen % 8;
+        error("Tabulations are not allowed for identation. Use spaces instead.");
+        indentLen++;
         pos++;
       } else if (c == '\n') { // entirely blank line: discard
         indentLen = 0;