diff --git a/Documentation/git-format-patch.txt b/Documentation/git-format-patch.txt
index 369af2c4a7..8708b31593 100644
--- a/Documentation/git-format-patch.txt
+++ b/Documentation/git-format-patch.txt
@@ -357,6 +357,11 @@ material (this may change in the future).
 	between the previous and current series of patches by adjusting the
 	creation/deletion cost fudge factor. See linkgit:git-range-diff[1])
 	for details.
++
+Defaults to 999 (the linkgit:git-range-diff[1] uses 60), as the use
+case is to show comparison with an older iteration of the same
+topic and the tool should find more correspondence between the two
+sets of patches.
 
 --notes[=<ref>]::
 --no-notes::
diff --git a/builtin/log.c b/builtin/log.c
index b17dd8b40a..c8ce0c0d88 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -2296,7 +2296,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 	}
 
 	if (creation_factor < 0)
-		creation_factor = RANGE_DIFF_CREATION_FACTOR_DEFAULT;
+		creation_factor = CREATION_FACTOR_FOR_THE_SAME_SERIES;
 	else if (!rdiff_prev)
 		die(_("the option '%s' requires '%s'"), "--creation-factor", "--range-diff");
 
diff --git a/range-diff.h b/range-diff.h
index 04ffe217be..2f69f6a434 100644
--- a/range-diff.h
+++ b/range-diff.h
@@ -6,6 +6,12 @@
 
 #define RANGE_DIFF_CREATION_FACTOR_DEFAULT 60
 
+/*
+ * A much higher value than the default, when we KNOW we are comparing
+ * the same series (e.g., used when format-patch calls range-diff).
+ */
+#define CREATION_FACTOR_FOR_THE_SAME_SERIES 999
+
 struct range_diff_options {
 	int creation_factor;
 	unsigned dual_color:1;