diff --git a/Modules/_testinternalcapi/tokenizer.c b/Modules/_testinternalcapi/tokenizer.c
index c45450b398a5d8b..1f89c12f223c7d9 100644
--- a/Modules/_testinternalcapi/tokenizer.c
+++ b/Modules/_testinternalcapi/tokenizer.c
@@ -45,34 +45,24 @@ test_tokenizer_source(PyObject *Py_UNUSED(module),
         goto error;
     }
 
-    _PyTok_Loc loc;
-    _PyTok_Line line;
-    if (check(_PyTok_SourceLocation(
-                  &source, 0, _PYTOK_AFFINITY_RIGHT, &loc) == 0,
-              "cannot locate empty source") < 0 ||
-            check(loc.lineno == 1 && loc.byte_col == 0,
-                  "wrong empty source location") < 0 ||
-            check(_PyTok_SourceLine(&source, 1, &line) == 0,
-                  "cannot find empty source line") < 0 ||
-            check(line.start == 0 && line.end == 0,
-                  "wrong empty source line") < 0 ||
-            check_system_error(
-                _PyTok_SourceAppendLine(&source, "", 0, 0) < 0,
-                "accepted empty source line") < 0 ||
+    if (check_system_error(
+            _PyTok_SourceAppendLine(&source, "", 0, 0) < 0,
+            "accepted empty source line") < 0 ||
             check_system_error(
                 _PyTok_SourceAppendLine(&source, "a\nb\n", 4, 0) < 0,
                 "accepted multiple source lines") < 0 ||
             check_system_error(
                 _PyTok_SourceAppendLine(&source, "a", 1, 1) < 0,
-                "accepted missing implicit newline") < 0) {
-        goto error;
-    }
-
-    if (check(_PyTok_SourceAppendLine(&source, "alpha\n", 6, 0) == 0,
-              "wrong first source offset") < 0 ||
+                "accepted missing implicit newline") < 0 ||
+            check(_PyTok_SourceAppendLine(
+                      &source, "alpha\n", 6, 0) == 0,
+                  "wrong first source offset") < 0 ||
             check(_PyTok_SourceAppendLine(
                       &source, "\xce\xb2\n", 3, 1) == 6,
-                  "wrong second source offset") < 0) {
+                  "wrong second source offset") < 0 ||
+            check(!_PyTok_SourceLineIsImplicit(&source, 1) &&
+                      _PyTok_SourceLineIsImplicit(&source, 2),
+                  "wrong implicit newline flags") < 0) {
         goto error;
     }
 
@@ -84,159 +74,24 @@ test_tokenizer_source(PyObject *Py_UNUSED(module),
         goto error;
     }
 
-    if (check(_PyTok_SourceAppendLine(&source, "nul\0x\n", 6, 0) == 9,
-              "wrong third source offset") < 0) {
-        goto error;
-    }
-
-    int marker_line = 257;
-    int final_line = 300;
-    _PyTok_Off marker_start = -1;
-    for (int lineno = 4; lineno <= final_line; lineno++) {
-        const char *text = lineno == marker_line ? "marker\n" : "x\n";
-        Py_ssize_t len = (Py_ssize_t)strlen(text);
-        _PyTok_Off start = _PyTok_SourceAppendLine(
-            &source, text, len, lineno == final_line);
-        if (start < 0) {
-            goto error;
-        }
-        if (lineno == marker_line) {
-            marker_start = start;
-        }
-    }
-
-    if (check(source.nlines == final_line, "wrong source line count") < 0 ||
-            check(_PyTok_SourceLine(&source, marker_line, &line) == 0,
-                  "cannot find late source line") < 0 ||
-            check(line.start == marker_start &&
-                      line.end == marker_start + 7,
-                  "wrong late source line") < 0 ||
-            check(!line.implicit_newline && !line.contains_nul,
-                  "wrong late source flags") < 0 ||
-            check(_PyTok_SourceLine(&source, 2, &line) == 0,
-                  "cannot find second source line") < 0 ||
-            check(line.start == 6 && line.end == 9 &&
-                      line.implicit_newline && !line.contains_nul,
-                  "wrong second source line") < 0 ||
-            check(!_PyTok_SourceLineIsImplicit(&source, 1) &&
-                      _PyTok_SourceLineIsImplicit(&source, 2),
-                  "wrong early implicit newline flags") < 0 ||
-            check(_PyTok_SourceLine(&source, 3, &line) == 0,
-                  "cannot find third source line") < 0 ||
-            check(line.contains_nul, "missing null byte flag") < 0 ||
-            check(_PyTok_SourceLine(&source, final_line, &line) == 0,
-                  "cannot find final source line") < 0 ||
-            check(line.implicit_newline &&
-                      _PyTok_SourceLineIsImplicit(&source, final_line),
-                  "missing late implicit newline flag") < 0) {
-        goto error;
-    }
-
-    Py_ssize_t view_len;
-    const char *view = _PyTok_SourceSpanView(
-        &source, _PyTok_SpanFromBounds(6, 8), &view_len);
-    if (check(view != NULL && view_len == 2 &&
-                  memcmp(view, "\xce\xb2", 2) == 0,
-              "wrong source span view") < 0 ||
-            check(_PyTok_SourceLocation(
-                      &source, marker_start,
-                      _PYTOK_AFFINITY_LEFT, &loc) == 0,
-                  "cannot locate left line boundary") < 0 ||
-            check(loc.lineno == marker_line - 1 && loc.byte_col == 2,
-                  "wrong left boundary location") < 0 ||
-            check(_PyTok_SourceLocation(
-                      &source, marker_start,
-                      _PYTOK_AFFINITY_RIGHT, &loc) == 0,
-                  "cannot locate right line boundary") < 0 ||
-            check(loc.lineno == marker_line && loc.byte_col == 0,
-                  "wrong right boundary location") < 0 ||
-            check(_PyTok_SourceLocation(
-                      &source, marker_start + 1,
-                      _PYTOK_AFFINITY_RIGHT, &loc) == 0,
-                  "cannot locate late source byte") < 0 ||
-            check(loc.lineno == marker_line && loc.byte_col == 1,
-                  "wrong late source location") < 0) {
-        goto error;
-    }
-
-    if (check(_PyTok_SourceLocation(
-                  &source, source.len, _PYTOK_AFFINITY_LEFT, &loc) == 0,
-              "cannot locate left EOF") < 0 ||
-            check(loc.lineno == final_line && loc.byte_col == 2,
-                  "wrong left EOF location") < 0 ||
-            check(_PyTok_SourceLocation(
-                      &source, source.len,
-                      _PYTOK_AFFINITY_RIGHT, &loc) == 0,
-                  "cannot locate right EOF") < 0 ||
-            check(loc.lineno == final_line + 1 && loc.byte_col == 0,
-                  "wrong right EOF location") < 0 ||
-            check(_PyTok_SourceLine(&source, final_line + 1, &line) == 0,
-                  "cannot find virtual EOF line") < 0 ||
-            check(line.start == source.len && line.end == source.len,
-                  "wrong virtual EOF line") < 0 ||
-            check(!_PyTok_SourceLineIsImplicit(&source, 0) &&
-                      !_PyTok_SourceLineIsImplicit(
-                          &source, final_line + 1),
-                  "virtual or invalid line is implicit") < 0) {
-        goto error;
-    }
-
-    view = _PyTok_SourceSpanView(
-        &source, _PyTok_SpanFromBounds(0, source.len + 1), &view_len);
-    if (check_system_error(view == NULL, "accepted invalid source span") < 0 ||
-            check_system_error(
-                _PyTok_SourceLocation(
-                    &source, source.len + 1,
-                    _PYTOK_AFFINITY_RIGHT, &loc) < 0,
-                "accepted invalid source offset") < 0 ||
-            check_system_error(
-                _PyTok_SourceLine(&source, final_line + 2, &line) < 0,
-                "accepted invalid source line") < 0) {
+    if (check(source.len == 9 &&
+                  memcmp(source.bytes, "alpha\n\xce\xb2\n", 10) == 0,
+              "wrong source contents") < 0) {
         goto error;
     }
 
     _PyTok_SourceClear(&source);
-    _PyTok_SourceInit(&source);
     if (_PyTok_SourceAppendLine(&source, "tail", 4, 0) < 0 ||
             check_system_error(
                 _PyTok_SourceAppendLine(&source, "x\n", 2, 0) < 0,
-                "appended after unterminated source line") < 0 ||
-            check(_PyTok_SourceLocation(
-                      &source, source.len,
-                      _PYTOK_AFFINITY_RIGHT, &loc) == 0,
-                  "cannot locate unterminated EOF") < 0 ||
-            check(loc.lineno == 1 && loc.byte_col == 4,
-                  "wrong unterminated EOF location") < 0) {
+                "appended after unterminated source line") < 0) {
         goto error;
     }
-
     if (check_line_view(&source, 1, "tail") < 0 ||
             check_line_view(&source, PY_SSIZE_T_MAX, "tail") < 0) {
         goto error;
     }
 
-    _PyTok_SourceDiscard(&source);
-    if (check(_PyTok_SourceAppendLine(&source, "a\n", 2, 0) == 4,
-              "wrong retained source offset") < 0 ||
-            _PyTok_SourceLine(&source, 1, &line) < 0 ||
-            check(line.start == 4 && line.end == 6,
-                  "wrong retained source line") < 0 ||
-            _PyTok_SourceLocation(
-                &source, 4, _PYTOK_AFFINITY_LEFT, &loc) < 0 ||
-            check(loc.lineno == 1 && loc.byte_col == 0,
-                  "wrong retained source location") < 0) {
-        goto error;
-    }
-    view = _PyTok_SourceSpanView(
-        &source, _PyTok_SpanFromBounds(4, 5), &view_len);
-    if (check(view != NULL && view_len == 1 && view[0] == 'a',
-              "wrong retained source span") < 0 ||
-            check_system_error(_PyTok_SourceSpanView(
-                &source, _PyTok_SpanFromBounds(0, 1), &view_len) == NULL,
-                "accepted discarded source span") < 0) {
-        goto error;
-    }
-
     _PyTok_SourceClear(&source);
     Py_RETURN_NONE;
 
diff --git a/Parser/tokenizer/source.c b/Parser/tokenizer/source.c
index 989944afd9fea96..d69eab93923e81c 100644
--- a/Parser/tokenizer/source.c
+++ b/Parser/tokenizer/source.c
@@ -2,8 +2,6 @@
 
 #include "source.h"
 
-#define LINE_CHECKPOINT_INTERVAL 256
-
 void
 _PyTok_SourceInit(_PyTok_SourceText *source)
 {
@@ -14,7 +12,6 @@ void
 _PyTok_SourceClear(_PyTok_SourceText *source)
 {
     PyMem_Free(source->bytes);
-    PyMem_Free(source->line_checkpoints);
     PyMem_Free(source->implicit_lines);
     _PyTok_SourceInit(source);
 }
@@ -74,34 +71,6 @@ reserve_bytes(_PyTok_SourceText *source, Py_ssize_t needed)
     return 0;
 }
 
-static int
-reserve_checkpoints(_PyTok_SourceText *source, int needed)
-{
-    if (needed <= source->checkpoints_cap) {
-        return 0;
-    }
-    int cap;
-    if (source->checkpoints_cap == 0) {
-        cap = 16;
-    }
-    else if (source->checkpoints_cap <= INT_MAX / 2) {
-        cap = source->checkpoints_cap * 2;
-    }
-    else {
-        PyErr_NoMemory();
-        return -1;
-    }
-    _PyTok_Off *checkpoints = source->line_checkpoints;
-    PyMem_Resize(checkpoints, _PyTok_Off, cap);
-    if (checkpoints == NULL) {
-        PyErr_NoMemory();
-        return -1;
-    }
-    source->line_checkpoints = checkpoints;
-    source->checkpoints_cap = cap;
-    return 0;
-}
-
 static int
 reserve_implicit_lines(_PyTok_SourceText *source, int nlines)
 {
@@ -165,11 +134,7 @@ _PyTok_SourceAppendLine(_PyTok_SourceText *source, const char *bytes,
         return -1;
     }
     int nlines = source->nlines + 1;
-    int checkpoint = ((nlines - 1) % LINE_CHECKPOINT_INTERVAL) == 0;
-    int checkpoint_count = (nlines - 1) / LINE_CHECKPOINT_INTERVAL + 1;
-    if ((checkpoint &&
-         reserve_checkpoints(source, checkpoint_count) < 0) ||
-            (implicit_newline && reserve_implicit_lines(source, nlines) < 0) ||
+    if ((implicit_newline && reserve_implicit_lines(source, nlines) < 0) ||
             reserve_bytes(source, source->len + len + 1) < 0) {
         return -1;
     }
@@ -178,10 +143,6 @@ _PyTok_SourceAppendLine(_PyTok_SourceText *source, const char *bytes,
     memcpy(source->bytes + start, bytes, len);
     source->len += len;
     source->bytes[source->len] = '\0';
-    if (checkpoint) {
-        source->line_checkpoints[checkpoint_count - 1] =
-            source->base_offset + start;
-    }
     if (implicit_newline) {
         source->implicit_lines[(nlines - 1) / 8] |=
             (unsigned char)(1U << ((nlines - 1) & 7));
@@ -210,19 +171,6 @@ _PyTok_SourceLineView(const _PyTok_SourceText *source, Py_ssize_t lineno,
     return line;
 }
 
-const char *
-_PyTok_SourceSpanView(const _PyTok_SourceText *source, _PyTok_Span span,
-                      Py_ssize_t *len)
-{
-    if (!_PyTok_SpanIsValid(span) || span.start < source->base_offset ||
-            span.end - source->base_offset > source->len || len == NULL) {
-        PyErr_SetString(PyExc_SystemError, "invalid tokenizer source span");
-        return NULL;
-    }
-    *len = span.end - span.start;
-    return _PyTok_SourceData(source) + (span.start - source->base_offset);
-}
-
 int
 _PyTok_SourceLineIsImplicit(const _PyTok_SourceText *source, int lineno)
 {
@@ -233,124 +181,3 @@ _PyTok_SourceLineIsImplicit(const _PyTok_SourceText *source, int lineno)
     return (source->implicit_lines[(lineno - 1) / 8] >>
             ((lineno - 1) & 7)) & 1;
 }
-
-static int
-source_ends_in_newline(const _PyTok_SourceText *source)
-{
-    return source->len > 0 && source->bytes[source->len - 1] == '\n';
-}
-
-static int
-eof_lineno(const _PyTok_SourceText *source)
-{
-    if (source->nlines == 0) {
-        return 1;
-    }
-    return source->nlines + source_ends_in_newline(source);
-}
-
-int
-_PyTok_SourceLine(const _PyTok_SourceText *source, int lineno,
-                  _PyTok_Line *line)
-{
-    if (line == NULL || lineno < 1 || lineno > eof_lineno(source)) {
-        PyErr_SetString(PyExc_SystemError, "invalid tokenizer source line");
-        return -1;
-    }
-    if (lineno > source->nlines) {
-        *line = (_PyTok_Line){
-            .start = source->base_offset + source->len,
-            .end = source->base_offset + source->len,
-        };
-        return 0;
-    }
-
-    int checkpoint = (lineno - 1) / LINE_CHECKPOINT_INTERVAL;
-    int current = checkpoint * LINE_CHECKPOINT_INTERVAL + 1;
-    _PyTok_Off start = source->line_checkpoints[checkpoint];
-    while (current < lineno) {
-        start = _PyTok_SourceFindLineEnd(source, start);
-        if (start < 0) {
-            return -1;
-        }
-        current++;
-    }
-    _PyTok_Off end = source->base_offset + source->len;
-    if (lineno < source->nlines) {
-        end = _PyTok_SourceFindLineEnd(source, start);
-        if (end < 0) {
-            return -1;
-        }
-    }
-    *line = (_PyTok_Line){
-        .start = start,
-        .end = end,
-        .implicit_newline = _PyTok_SourceLineIsImplicit(source, lineno),
-        .contains_nul = memchr(
-            source->bytes + (start - source->base_offset),
-            0, end - start) != NULL,
-    };
-    return 0;
-}
-
-int
-_PyTok_SourceLocation(const _PyTok_SourceText *source, _PyTok_Off offset,
-                      _PyTok_Affinity affinity, _PyTok_Loc *loc)
-{
-    if (offset < source->base_offset ||
-            offset - source->base_offset > source->len || loc == NULL ||
-            (affinity != _PYTOK_AFFINITY_LEFT &&
-             affinity != _PYTOK_AFFINITY_RIGHT)) {
-        PyErr_SetString(PyExc_SystemError, "invalid tokenizer source offset");
-        return -1;
-    }
-    if (source->nlines == 0 ||
-            (offset - source->base_offset == source->len &&
-             source_ends_in_newline(source) &&
-             affinity == _PYTOK_AFFINITY_RIGHT)) {
-        *loc = (_PyTok_Loc){eof_lineno(source), 0};
-        return 0;
-    }
-
-    _PyTok_Off key = offset;
-    if (affinity == _PYTOK_AFFINITY_LEFT && key > source->base_offset) {
-        key--;
-    }
-    int low = 0;
-    int high = (source->nlines - 1) / LINE_CHECKPOINT_INTERVAL + 1;
-    while (low < high) {
-        int middle = low + (high - low) / 2;
-        if (source->line_checkpoints[middle] <= key) {
-            low = middle + 1;
-        }
-        else {
-            high = middle;
-        }
-    }
-    int checkpoint = low - 1;
-    if (checkpoint < 0) {
-        PyErr_SetString(PyExc_SystemError, "corrupt tokenizer source line index");
-        return -1;
-    }
-    int lineno = checkpoint * LINE_CHECKPOINT_INTERVAL + 1;
-    _PyTok_Off start = source->line_checkpoints[checkpoint];
-    while (lineno < source->nlines) {
-        _PyTok_Off end = _PyTok_SourceFindLineEnd(source, start);
-        if (end < 0) {
-            return -1;
-        }
-        if (offset < end ||
-                (offset == end && affinity == _PYTOK_AFFINITY_LEFT)) {
-            break;
-        }
-        start = end;
-        lineno++;
-    }
-    _PyTok_Off byte_col = offset - start;
-    if (byte_col > INT_MAX) {
-        PyErr_SetString(PyExc_OverflowError, "tokenizer column is too large");
-        return -1;
-    }
-    *loc = (_PyTok_Loc){lineno, (int)byte_col};
-    return 0;
-}
diff --git a/Parser/tokenizer/source.h b/Parser/tokenizer/source.h
index 2d9c4f479123096..6972caf8a36aa24 100644
--- a/Parser/tokenizer/source.h
+++ b/Parser/tokenizer/source.h
@@ -18,28 +18,13 @@ typedef struct {
     int byte_col;
 } _PyTok_Loc;
 
-typedef enum {
-    _PYTOK_AFFINITY_LEFT,
-    _PYTOK_AFFINITY_RIGHT,
-} _PyTok_Affinity;
-
-/* The half-open range includes the terminating newline when present. */
-typedef struct {
-    _PyTok_Off start;
-    _PyTok_Off end;
-    unsigned implicit_newline : 1;
-    unsigned contains_nul : 1;
-} _PyTok_Line;
-
 typedef struct {
     char *bytes;
     _PyTok_Off base_offset;
     _PyTok_Off len;
     _PyTok_Off cap;
-    _PyTok_Off *line_checkpoints;
     unsigned char *implicit_lines;
     int nlines;
-    int checkpoints_cap;
     Py_ssize_t implicit_cap;
 } _PyTok_SourceText;
 
@@ -68,20 +53,9 @@ PyAPI_FUNC(_PyTok_Off) _PyTok_SourceAppendLine(
    This does not set an exception. Append, discard, and clear invalidate the view. */
 PyAPI_FUNC(const char *) _PyTok_SourceLineView(
     const _PyTok_SourceText *source, Py_ssize_t lineno, Py_ssize_t *len);
-/* The returned view is invalidated by SourceAppendLine and SourceClear. */
-PyAPI_FUNC(const char *) _PyTok_SourceSpanView(
-    const _PyTok_SourceText *, _PyTok_Span, Py_ssize_t *);
-/* Look up a 1-based line in the retained window. Empty and newline-terminated
-   sources have an empty virtual line at EOF. */
-PyAPI_FUNC(int) _PyTok_SourceLine(
-    const _PyTok_SourceText *, int, _PyTok_Line *);
 /* Return false for invalid line numbers and the virtual EOF line. */
 PyAPI_FUNC(int) _PyTok_SourceLineIsImplicit(
     const _PyTok_SourceText *, int);
-/* At a line boundary, left affinity selects the preceding line at its end;
-   right affinity selects the following line at byte column zero. */
-PyAPI_FUNC(int) _PyTok_SourceLocation(
-    const _PyTok_SourceText *, _PyTok_Off, _PyTok_Affinity, _PyTok_Loc *);
 
 static inline _PyTok_Span
 _PyTok_SpanFromBounds(_PyTok_Off start, _PyTok_Off end)
@@ -95,24 +69,4 @@ _PyTok_SpanIsValid(_PyTok_Span span)
     return span.start >= 0 && span.end >= span.start;
 }
 
-static inline _PyTok_Off
-_PyTok_SourceFindLineEnd(const _PyTok_SourceText *source, _PyTok_Off start)
-{
-    if (source->bytes == NULL || start < source->base_offset ||
-            start - source->base_offset >= source->len) {
-        PyErr_SetString(PyExc_SystemError,
-                        "corrupt tokenizer source line index");
-        return -1;
-    }
-    _PyTok_Off relative_start = start - source->base_offset;
-    const char *newline = memchr(
-        source->bytes + relative_start, '\n', source->len - relative_start);
-    if (newline == NULL) {
-        PyErr_SetString(PyExc_SystemError,
-                        "corrupt tokenizer source line index");
-        return -1;
-    }
-    return source->base_offset + (newline - source->bytes) + 1;
-}
-
 #endif