diff --git a/extras/conf/SRB2-22.cfg b/extras/conf/SRB2-22.cfg
index 952ce6969..ae905b637 100644
--- a/extras/conf/SRB2-22.cfg
+++ b/extras/conf/SRB2-22.cfg
@@ -2341,6 +2341,7 @@ linedeftypes
 		{
 			title = "Enable/Disable Gravity Flip";
 			prefix = "(433)";
+			flags2text = "[1] Force MFE_VERTICALFLIP";
 			flags8text = "[3] Set delay by backside sector";
 			flags32text = "[5] Invert current gravity";
 			flags64text = "[6] Return to normal";
diff --git a/extras/conf/udb/Includes/SRB222_linedefs.cfg b/extras/conf/udb/Includes/SRB222_linedefs.cfg
index 99c305659..3a3bd80cc 100644
--- a/extras/conf/udb/Includes/SRB222_linedefs.cfg
+++ b/extras/conf/udb/Includes/SRB222_linedefs.cfg
@@ -4223,6 +4223,16 @@ udmf
 					1 = "Yes";
 				}
 			}
+			arg2
+			{
+				title = "Force MFE_VERTICALFLIP";
+				type = 11;
+				enum
+				{
+					0 = "No";
+					1 = "Yes";
+				}
+			}
 		}
 
 		434
diff --git a/src/p_setup.c b/src/p_setup.c
index d6cda7d4f..dc1111531 100644
--- a/src/p_setup.c
+++ b/src/p_setup.c
@@ -5299,6 +5299,7 @@ static void P_ConvertBinaryLinedefTypes(void)
 		case 433: //Enable/disable gravity flip
 			lines[i].args[0] = !!(lines[i].flags & ML_NOCLIMB);
 			lines[i].args[1] = !!(lines[i].flags & ML_SKEWTD);
+			lines[i].args[2] = !!(lines[i].flags & ML_BLOCKMONSTERS);
 			break;
 		case 434: //Award power-up
 			if (sides[lines[i].sidenum[0]].text)
diff --git a/src/p_spec.c b/src/p_spec.c
index 4e6ef531f..6f798421a 100644
--- a/src/p_spec.c
+++ b/src/p_spec.c
@@ -2786,6 +2786,8 @@ static void P_ProcessLineSpecial(line_t *line, mobj_t *mo, sector_t *callsec)
 				mo->flags2 &= ~MF2_OBJECTFLIP;
 			else
 				mo->flags2 |= MF2_OBJECTFLIP;
+			if (line->args[2])
+				mo->eflags |= MFE_VERTICALFLIP;
 			if (bot)
 				bot->flags2 = (bot->flags2 & ~MF2_OBJECTFLIP) | (mo->flags2 & MF2_OBJECTFLIP);
 			break;