diff --git a/src/main.c b/src/main.c
index 03fb60bf..7b3f05e1 100644
--- a/src/main.c
+++ b/src/main.c
@@ -385,6 +385,23 @@ void FromDSE(int dse, int *y, int *m, int *d)
     return;
 }
 
+int JulianToGregorianOffset(int y, int m)
+{
+    int offset = 13;
+    int centuries;
+    int four_centuries;
+    if (y >= 2100) {
+        centuries = (y - 2000) / 100;
+        four_centuries = (y - 2000) / 400;
+        offset += centuries - four_centuries;
+        if (!(y%100) && (y % 400)) {
+            if (m < 2) {
+                offset--;  /* Offset increments in March */
+            }
+        }
+    }
+    return offset;
+}
 /***************************************************************/
 /*                                                             */
 /*  ParseChar                                                  */
diff --git a/src/protos.h b/src/protos.h
index e9cb2e24..6d9b0393 100644
--- a/src/protos.h
+++ b/src/protos.h
@@ -58,6 +58,7 @@ void InitRemind (int argc, char const *argv[]);
 void Usage (void);
 int DSE (int year, int month, int day);
 void FromDSE (int dse, int *y, int *m, int *d);
+int JulianToGregorianOffset(int y, int m);
 int ParseChar (ParsePtr p, int *err, int peek);
 int ParseToken (ParsePtr p, DynamicBuffer *dbuf);
 int ParseIdentifier (ParsePtr p, DynamicBuffer *dbuf);