diff --git a/dda_lookahead.c b/dda_lookahead.c
index 949cc19..05573b0 100644
--- a/dda_lookahead.c
+++ b/dda_lookahead.c
@@ -172,7 +172,7 @@ void dda_join_moves(DDA *prev, DDA *current) {
   // until then, we do not want to touch the current move settings.
   // Note: we assume 'current' will not be dispatched while this function runs, so we do not to
   // back up the move settings: they will remain constant.
-  uint32_t this_F, this_F_in_steps, this_F_start_in_steps, this_rampup, this_rampdown, this_total_steps;
+  uint32_t this_F, this_F_in_steps, this_F_start_in_steps, this_rampup, this_rampdown, this_total_steps, this_fast_axis;
   uint8_t this_id;
   static uint32_t la_cnt = 0;     // Counter: how many moves did we join?
   #ifdef LOOKAHEAD_DEBUG
@@ -203,6 +203,7 @@ void dda_join_moves(DDA *prev, DDA *current) {
       this_id = current->id;
       this_F = current->endpoint.F;
       this_total_steps = current->total_steps;
+      this_fast_axis = current->fast_axis;
     ATOMIC_END
 
     // Here we have to distinguish between feedrate along the movement
@@ -217,10 +218,9 @@ void dda_join_moves(DDA *prev, DDA *current) {
     this_F = muldiv(current->fast_um, current->endpoint.F, current->distance);
     crossF = muldiv(current->fast_um, crossF, current->distance);
 
-    // TODO: calculate the steps from the fastest axis and not from X.
-    prev_F_in_steps = ACCELERATE_RAMP_LEN(prev_F);
-    this_F_in_steps = ACCELERATE_RAMP_LEN(this_F);
-    crossF_in_steps = ACCELERATE_RAMP_LEN(crossF);
+    prev_F_in_steps = acc_ramp_len(prev_F, this_fast_axis);
+    this_F_in_steps = acc_ramp_len(this_F, this_fast_axis);
+    crossF_in_steps = acc_ramp_len(crossF, this_fast_axis);
 
     // Show the proposed crossing speed - this might get adjusted below
     if (DEBUG_DDA && (debug_flags & DEBUG_DDA))
diff --git a/dda_maths.h b/dda_maths.h
index 34a2eda..c0fb7b6 100644
--- a/dda_maths.h
+++ b/dda_maths.h
@@ -53,7 +53,4 @@ const uint8_t msbloc (uint32_t v);
 // Calculates acceleration ramp length in steps.
 uint32_t acc_ramp_len(uint32_t feedrate, uint8_t fast_axis);
 
-// For X axis only, should become obsolete:
-#define ACCELERATE_RAMP_LEN(speed) (((speed)*(speed)) / (uint32_t)((7200000.0f * ACCELERATION) / (float)STEPS_PER_M_X))
-
 #endif	/* _DDA_MATHS_H */