diff --git a/compiler/rustc_parse/src/parser/mod.rs b/compiler/rustc_parse/src/parser/mod.rs
index 9a63a205242..33900503520 100644
--- a/compiler/rustc_parse/src/parser/mod.rs
+++ b/compiler/rustc_parse/src/parser/mod.rs
@@ -425,6 +425,11 @@ pub fn new(
         // Make parser point to the first token.
         parser.bump();
 
+        // Change this from 1 back to 0 after the bump. This eases debugging of
+        // `Parser::collect_tokens_trailing_token` nicer because it makes the
+        // token positions 0-indexed which is nicer than 1-indexed.
+        parser.num_bump_calls = 0;
+
         parser
     }
 
diff --git a/compiler/rustc_parse/src/parser/tests.rs b/compiler/rustc_parse/src/parser/tests.rs
index cf791d332a2..491aa71155a 100644
--- a/compiler/rustc_parse/src/parser/tests.rs
+++ b/compiler/rustc_parse/src/parser/tests.rs
@@ -1522,7 +1522,7 @@ fn debug_lookahead() {
         },
     },
     tokens: [],
-    approx_token_stream_pos: 1,
+    approx_token_stream_pos: 0,
     ..
 }"
         );
@@ -1566,7 +1566,7 @@ fn debug_lookahead() {
             Parenthesis,
         ),
     ],
-    approx_token_stream_pos: 1,
+    approx_token_stream_pos: 0,
     ..
 }"
         );
@@ -1631,7 +1631,7 @@ fn debug_lookahead() {
         Semi,
         Eof,
     ],
-    approx_token_stream_pos: 1,
+    approx_token_stream_pos: 0,
     ..
 }"
         );
@@ -1663,7 +1663,7 @@ fn debug_lookahead() {
             No,
         ),
     ],
-    approx_token_stream_pos: 9,
+    approx_token_stream_pos: 8,
     ..
 }"
         );
@@ -1701,7 +1701,7 @@ fn debug_lookahead() {
             No,
         ),
     ],
-    approx_token_stream_pos: 9,
+    approx_token_stream_pos: 8,
     ..
 }"
         );
@@ -1728,7 +1728,7 @@ fn debug_lookahead() {
     tokens: [
         Eof,
     ],
-    approx_token_stream_pos: 15,
+    approx_token_stream_pos: 14,
     ..
 }"
         );