diff --git a/src/mesa/tnl/t_draw.c b/src/mesa/tnl/t_draw.c
index fdde294..023573c 100644
--- a/src/mesa/tnl/t_draw.c
+++ b/src/mesa/tnl/t_draw.c
@@ -378,8 +378,22 @@ void _tnl_vbo_draw_prims(GLcontext *ctx,
 			 GLuint min_index,
 			 GLuint max_index)
 {
-   if (!index_bounds_valid)
-      vbo_get_minmax_index(ctx, prim, ib, &min_index, &max_index);
+   if (!index_bounds_valid) {
+      /* find min/max of all primitives' indexes */
+      GLuint i;
+      for (i = 0; i < nr_prims; i++) {
+         GLuint min, max;
+         vbo_get_minmax_index(ctx, prim + i, ib, &min, &max);
+         if (i == 0) {
+            min_index = min;
+            max_index = max;
+         }
+         else {
+            min_index = MIN2(min_index, min);
+            max_index = MAX2(max_index, max);
+         }
+      }
+   }
 
    _tnl_draw_prims(ctx, arrays, prim, nr_prims, ib, min_index, max_index);
 }
diff --git a/src/mesa/vbo/vbo_exec_array.c b/src/mesa/vbo/vbo_exec_array.c
index c32a504..1a53034 100644
--- a/src/mesa/vbo/vbo_exec_array.c
+++ b/src/mesa/vbo/vbo_exec_array.c
@@ -49,7 +49,8 @@ vbo_get_minmax_index(GLcontext *ctx,
 		     GLuint *min_index, GLuint *max_index)
 {
    GLuint i;
-   GLuint count = prim->count;
+   const GLuint start = prim->start;
+   const GLuint count = prim->count;
    const void *indices;
 
    if (_mesa_is_bufferobj(ib->obj)) {
@@ -61,9 +62,10 @@ vbo_get_minmax_index(GLcontext *ctx,
       indices = ib->ptr;
    }
 
+   /* scan the indexes from 'start' through 'start+count-1' */
    switch (ib->type) {
    case GL_UNSIGNED_INT: {
-      const GLuint *ui_indices = (const GLuint *)indices;
+      const GLuint *ui_indices = (const GLuint *)indices + start;
       GLuint max_ui = ui_indices[count-1];
       GLuint min_ui = ui_indices[0];
       for (i = 0; i < count; i++) {
@@ -75,7 +77,7 @@ vbo_get_minmax_index(GLcontext *ctx,
       break;
    }
    case GL_UNSIGNED_SHORT: {
-      const GLushort *us_indices = (const GLushort *)indices;
+      const GLushort *us_indices = (const GLushort *)indices + start;
       GLuint max_us = us_indices[count-1];
       GLuint min_us = us_indices[0];
       for (i = 0; i < count; i++) {
@@ -87,7 +89,7 @@ vbo_get_minmax_index(GLcontext *ctx,
       break;
    }
    case GL_UNSIGNED_BYTE: {
-      const GLubyte *ub_indices = (const GLubyte *)indices;
+      const GLubyte *ub_indices = (const GLubyte *)indices + start;
       GLuint max_ub = ub_indices[count-1];
       GLuint min_ub = ub_indices[0];
       for (i = 0; i < count; i++) {
@@ -1003,6 +1005,8 @@ vbo_validated_multidrawelements(GLcontext *ctx, GLenum mode,
    /* Check if we can handle this thing as a bunch of index offsets from the
     * same index pointer.  If we can't, then we have to fall back to doing
     * a draw_prims per primitive.
+    * Check that the difference between each prim's indexes is a multiple of
+    * the index/element size.
     */
    if (index_type_size != 1) {
       for (i = 0; i < primcount; i++) {