diff --git a/lib/images/math/backslash.xpm b/lib/images/math/backslash.xpm
index 04638511d4..e4addff495 100644
--- a/lib/images/math/backslash.xpm
+++ b/lib/images/math/backslash.xpm
@@ -2,7 +2,7 @@
 static char * backslash_xpm[] = {
 "7 23 2 1",
 " 	c None",
-".	c #5972FF",
+".	c black",
 ".      ",
 ".      ",
 ".      ",
diff --git a/lib/images/math/slash.xpm b/lib/images/math/slash.xpm
index 4a46f47762..9946dc7336 100644
--- a/lib/images/math/slash.xpm
+++ b/lib/images/math/slash.xpm
@@ -2,7 +2,7 @@
 static char * slash_xpm[] = {
 "7 23 2 1",
 " 	c None",
-".	c #5972FF",
+".	c black",
 "      .",
 "      .",
 "      .",