diff --git a/source/blender/blenkernel/intern/modifier.c b/source/blender/blenkernel/intern/modifier.c
index 243a24bc3b8..b805e3827d2 100644
--- a/source/blender/blenkernel/intern/modifier.c
+++ b/source/blender/blenkernel/intern/modifier.c
@@ -5067,7 +5067,28 @@ static void meshdeformModifier_do(
 	}
 
 	/* do deformation */
+	fac= 1.0f;
+
 	for(b=0; b<totvert; b++) {
+		if(dvert) {
+			for(dw=NULL, a=0; a<dvert[b].totweight; a++) {
+				if(dvert[b].dw[a].def_nr == defgrp_index) {
+					dw = &dvert[b].dw[a];
+					break;
+				}
+			}
+
+			if(mmd->flag & MOD_MDEF_INVERT_VGROUP) {
+				if(!dw) fac= 1.0f;
+				else if(dw->weight == 0.0f) continue;
+				else fac=1.0f-dw->weight;
+			}
+			else {
+				if(!dw) continue;
+				else fac= dw->weight;
+			}
+		}
+
 		totweight= 0.0f;
 		co[0]= co[1]= co[2]= 0.0f;
 
@@ -5080,20 +5101,6 @@ static void meshdeformModifier_do(
 		}
 
 		if(totweight > 0.0f) {
-			if(dvert) {
-				for(dw=NULL, a=0; a<dvert[b].totweight; a++) {
-					if(dvert[b].dw[a].def_nr == defgrp_index) {
-						dw = &dvert[b].dw[a];
-						break;
-					}
-				}
-				if(!dw) continue;
-
-				fac= dw->weight;
-			}
-			else
-				fac= 1.0f;
-
 			VecMulf(co, fac/totweight);
 			Mat3MulVecfl(icmat, co);
 			VECADD(vertexCos[b], vertexCos[b], co);
diff --git a/source/blender/makesdna/DNA_modifier_types.h b/source/blender/makesdna/DNA_modifier_types.h
index c8dcba4fae7..42016ad1c16 100644
--- a/source/blender/makesdna/DNA_modifier_types.h
+++ b/source/blender/makesdna/DNA_modifier_types.h
@@ -348,6 +348,8 @@ typedef struct BooleanModifierData {
 	int operation, pad;
 } BooleanModifierData;
 
+#define MOD_MDEF_INVERT_VGROUP (1<<0)
+
 typedef struct MeshDeformModifierData {
 	ModifierData modifier;
 
@@ -356,7 +358,7 @@ typedef struct MeshDeformModifierData {
 
 	float *bindweights, *bindcos;	/* computed binding weights */
 	short gridsize, needbind;
-	int pad;
+	short flag, pad;
 
 	int totvert, totcagevert;
 } MeshDeformModifierData;
diff --git a/source/blender/src/buttons_editing.c b/source/blender/src/buttons_editing.c
index 40e2643a390..c9bc9a4b296 100644
--- a/source/blender/src/buttons_editing.c
+++ b/source/blender/src/buttons_editing.c
@@ -2120,8 +2120,9 @@ static void draw_modifier(uiBlock *block, Object *ob, ModifierData *md, int *xco
 
 			uiBlockBeginAlign(block);
 			uiDefIDPoinBut(block, test_meshobpoin_but, ID_OB, B_CHANGEDEP, "Ob: ", lx, (cy-=19), buttonWidth,19, &mmd->object, "Mesh object to be use as cage"); 
-			but=uiDefBut(block, TEX, B_MODIFIER_RECALC, "VGroup: ",				  lx, (cy-=19), buttonWidth,19, &mmd->defgrp_name, 0.0, 31.0, 0, 0, "Vertex Group name to control overall meshdeform influence");
+			but=uiDefBut(block, TEX, B_MODIFIER_RECALC, "VGroup: ",				  lx, (cy-19), buttonWidth-40,19, &mmd->defgrp_name, 0.0, 31.0, 0, 0, "Vertex Group name to control overall meshdeform influence");
 			uiButSetCompleteFunc(but, autocomplete_vgroup, (void *)ob);
+			uiDefButBitS(block, TOG, MOD_MDEF_INVERT_VGROUP, B_MODIFIER_RECALC, "Inv", lx+buttonWidth-40, (cy-=19), 40,19, &mmd->flag, 0.0, 31.0, 0, 0, "Invert vertex group influence");
 
 			uiBlockBeginAlign(block);
 			if(mmd->bindweights) {