diff --git a/VERSION b/VERSION
index 97d67e1..5239f46 100644
--- a/VERSION
+++ b/VERSION
@@ -1,2 +1,2 @@
-2021 May 10 2021
+2021 May 19 2021
 
diff --git a/doc/CHANGES b/doc/CHANGES
index a79f7d6..c9651c4 100644
--- a/doc/CHANGES
+++ b/doc/CHANGES
@@ -14204,3 +14204,17 @@ argument is not a power of 2. Fix: changed the return
 to -1. The program does not crash but the midi file
 is not created correctly.
 
+
+
+May 10 2020
+
+abc2midi: the following file causes abc2midi to hang.
+
+X:1
+T: Hangs abc2midi
+L:1/4
+K:C
+2c/2fac'/c'/c'/c'/c'///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+
+James Allwright intoduced a fix in readlen() in parseabc.c
+
diff --git a/doc/readme.txt b/doc/readme.txt
index 6059e8b..69f6bc1 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 4.54 May 10 2021
+abc2midi version 4.55 May 19 2021
 abc2abc  version 2.13 May 08 2021
 yaps     version 1.86 December 10 2020
 abcmatch version 1.78 March 27 2021
diff --git a/parseabc.c b/parseabc.c
index 395705a..913b0db 100644
--- a/parseabc.c
+++ b/parseabc.c
@@ -543,37 +543,37 @@ void readsig (char **sig, timesig_details_t *timesig)
   }
 }
 
-void
-readlen (a, b, p)
-     int *a, *b;
-     char **p;
+
+void readlen (int *a, int *b, char **p)
 /* read length part of a note and advance character pointer */
 {
   int t;
 
   *a = readnump (p);
-  if (*a == 0)
-    {
-      *a = 1;
-    };
+  if (*a == 0) {
+    *a = 1;
+  }
   *b = 1;
-  if (**p == '/')
-    {
-      *p = *p + 1;
-      *b = readnump (p);
-      if (*b == 0)
-	{
-	  *b = 2;
-	  while (**p == '/')
-	    {
-	      *b = *b * 2;
-	      *p = *p + 1;
-	    };
-	};
-    };
+  if (**p == '/') {
+    *p = *p + 1;
+    *b = readnump (p);
+    if (*b == 0) {
+      *b = 2;
+      /* [JA] 2021-05-19 prevent infinite loop */
+      /* limit the number of '/'s we support */
+      while ((**p == '/') && (*b < 1024)) {
+        *b = *b * 2;
+        *p = *p + 1;
+      }
+      if (*b >= 1024) {
+        event_warning ("Exceeded maximum note denominator");
+      }
+    }
+  }
   *b = check_power_of_two(*b);
 }
 
+
 /* [JA] 2020-12-10 */
 static void read_L_unitlen(int *num, int *denom, char **place)
 {
diff --git a/store.c b/store.c
index d197fea..f3fca69 100644
--- a/store.c
+++ b/store.c
@@ -186,7 +186,7 @@ int main()
 
 */
 
-#define VERSION "4.54 May 10 2021 abc2midi" 
+#define VERSION "4.55 May 19 2021 abc2midi" 
 
 /* enables reading V: indication in header */
 #define XTEN1 1