diff --git a/VERSION b/VERSION
index e18f278..b0ff5f5 100644
--- a/VERSION
+++ b/VERSION
@@ -1,2 +1,2 @@
-2021 March 27 2021
+2021 March 30 2021
 
diff --git a/doc/CHANGES b/doc/CHANGES
index c6e3fc3..4dd5780 100644
--- a/doc/CHANGES
+++ b/doc/CHANGES
@@ -14136,3 +14136,19 @@ should be
 
 
 
+March 30 2021
+abc2midi bug: though grace notes only contain notes, the syntax allows
+you to substitute chords for grace notes. For example,
+
+X:1
+T:acc
+M:4/4
+L:1/4
+K:G
+[DF]|E {[bc]}B cd|D4|
+
+The function applygrace_new (in store.c) was modified so that the two notes
+in the chord [bc] are treated as if they were one note. Otherwise
+the measure would be too short (B is shrunk to make room for b and c)
+and there could be a loss of synchronization between the voices.
+
diff --git a/doc/readme.txt b/doc/readme.txt
index d4823e8..4245cc8 100644
--- a/doc/readme.txt
+++ b/doc/readme.txt
@@ -1,7 +1,7 @@
 abcMIDI :   abc <-> MIDI conversion utilities
 
 midi2abc version 3.47 November 01 2020
-abc2midi version 4.50 March 10 2021
+abc2midi version 4.51 March 30 2021
 abc2abc  version 2.12 October 19 2020
 yaps     version 1.86 December 10 2020
 abcmatch version 1.78 March 27 2021
diff --git a/store.c b/store.c
index 8f8a3fe..f0b17c0 100644
--- a/store.c
+++ b/store.c
@@ -186,7 +186,7 @@ int main()
 
 */
 
-#define VERSION "4.50 March 10 2021 abc2midi" 
+#define VERSION "4.51 March 30 2021 abc2midi" 
 
 /* enables reading V: indication in header */
 #define XTEN1 1
@@ -5245,7 +5245,9 @@ int place;
   int nextinchord;
   int hostnotestart, hostnoteend;
   int  adjusted_num, adjusted_den;
+  int notesinchord;
 
+  notesinchord = -1;
   j = place;
   start = -1;
   while ((j < notes) && (start == -1)) {
@@ -5307,11 +5309,26 @@ int place;
     grace_denom = 1;
     p = start;
     while (p <= end) {
-      if ((feature[p] == NOTE) || (feature[p] == REST)) {
-        grace_num = grace_num * denom[p] + grace_denom * num[p];
-        grace_denom = grace_denom * denom[p];
-        reduce(&grace_num, &grace_denom);
-      };
+      switch(feature[p]) { /* [SS] 2021-03-30 */
+      case NOTE:
+      case REST:
+        if (notesinchord <= 0) {
+           /* if chordal grace note, only count the first note */
+           grace_num = grace_num * denom[p] + grace_denom * num[p];
+           grace_denom = grace_denom * denom[p];
+           reduce(&grace_num, &grace_denom);
+           if (notesinchord == 0) notesinchord++;
+           }
+        break; 
+      case CHORDON:
+        notesinchord = 0;
+        break;
+      case CHORDOFF:
+        notesinchord = -1;
+        break;
+     default:
+        break;
+     }
       p = p + 1;
     };