diff --git a/src/libslic3r/Fill/FillBase.cpp b/src/libslic3r/Fill/FillBase.cpp
index 8cf4a2baf..56b018edf 100644
--- a/src/libslic3r/Fill/FillBase.cpp
+++ b/src/libslic3r/Fill/FillBase.cpp
@@ -33,8 +33,9 @@ Fill* Fill::new_from_type(const InfillPattern type)
     case ip3DHoneycomb:         return new Fill3DHoneycomb();
     case ipGyroid:              return new FillGyroid();
     case ipRectilinear:         return new FillRectilinear();
-    case ipMonotonic:          return new FillMonotonic();
     case ipRectilinearWGapFill: return new FillRectilinearWGapFill();
+    case ipMonotonic:           return new FillMonotonic();
+    case ipMonotonicWGapFill:   return new FillMonotonicWGapFill();
     case ipScatteredRectilinear:return new FillScatteredRectilinear();
     case ipLine:                return new FillLine();
     case ipGrid:                return new FillGrid();
diff --git a/src/libslic3r/Fill/FillRectilinear.cpp b/src/libslic3r/Fill/FillRectilinear.cpp
index ba21061ee..77b093b31 100644
--- a/src/libslic3r/Fill/FillRectilinear.cpp
+++ b/src/libslic3r/Fill/FillRectilinear.cpp
@@ -3328,7 +3328,7 @@ FillRectilinearWGapFill::fill_surface_extrusion(const Surface *surface, const Fi
     Polylines polylines_rectilinear;
     Surface rectilinear_surface{ *surface };
     FillParams params_monotonic = params;
-    params_monotonic.monotonic = true;
+    params_monotonic.monotonic = is_monotonic();
     for (const ExPolygon &rectilinear_area : rectilinear_areas) {
         rectilinear_surface.expolygon = rectilinear_area, 0 - 0.5 * params.flow.scaled_spacing();
         if (!fill_surface_by_lines(&rectilinear_surface, params_monotonic, 0.f, 0.f, polylines_rectilinear)) {
@@ -3368,7 +3368,7 @@ FillRectilinearWGapFill::fill_surface_extrusion(const Surface *surface, const Fi
         ExtrusionEntityCollection *eec = new ExtrusionEntityCollection();
         /// pass the no_sort attribute to the extrusion path
         //don't force monotonic if not top or bottom
-        if (surface->surface_type & (stPosTop | stPosBottom) != 0)
+        if (is_monotonic())
             eec->no_sort = true;
         else
             eec->no_sort = this->no_sort();
diff --git a/src/libslic3r/Fill/FillRectilinear.hpp b/src/libslic3r/Fill/FillRectilinear.hpp
index 7dcaefc27..0f372dbfd 100644
--- a/src/libslic3r/Fill/FillRectilinear.hpp
+++ b/src/libslic3r/Fill/FillRectilinear.hpp
@@ -126,11 +126,22 @@ public:
 class FillRectilinearWGapFill : public FillRectilinear
 {
 public:
-
     Fill* clone() const override { return new FillRectilinearWGapFill(*this); };
     ~FillRectilinearWGapFill() override = default;
     void fill_surface_extrusion(const Surface* surface, const FillParams& params, ExtrusionEntitiesPtr& out) const override;
     static void split_polygon_gap_fill(const Surface& surface, const FillParams& params, ExPolygons& rectilinear, ExPolygons& gapfill);
+protected:
+    virtual bool is_monotonic() const { return false;  }
+};
+
+class FillMonotonicWGapFill : public FillRectilinearWGapFill
+{
+public:
+
+    Fill* clone() const override { return new FillMonotonicWGapFill(*this); };
+    ~FillMonotonicWGapFill() override = default;
+protected:
+    virtual bool is_monotonic() const override { return true; }
 };
 
 
diff --git a/src/libslic3r/PrintConfig.cpp b/src/libslic3r/PrintConfig.cpp
index c8957dead..df7d39ff0 100644
--- a/src/libslic3r/PrintConfig.cpp
+++ b/src/libslic3r/PrintConfig.cpp
@@ -697,7 +697,7 @@ void PrintConfigDef::init_fff_params()
     def->cli = "top-fill-pattern|external-fill-pattern=s";
     def->enum_keys_map = &ConfigOptionEnum<InfillPattern>::get_enum_values();
     def->enum_values.push_back("rectilinear");
-    def->enum_values.push_back("rectilineargapfill");
+    def->enum_values.push_back("monotonicgapfillgapfill");
     def->enum_values.push_back("monotonic");
     def->enum_values.push_back("concentric");
     def->enum_values.push_back("concentricgapfill");
@@ -728,7 +728,7 @@ void PrintConfigDef::init_fff_params()
     def->cli = "bottom-fill-pattern|external-fill-pattern=s";
     def->enum_keys_map = &ConfigOptionEnum<InfillPattern>::get_enum_values();
     def->enum_values.push_back("rectilinear");
-    def->enum_values.push_back("rectilineargapfill");
+    def->enum_values.push_back("monotonicgapfill");
     def->enum_values.push_back("monotonic");
     def->enum_values.push_back("concentric");
     def->enum_values.push_back("concentricgapfill");
diff --git a/src/libslic3r/PrintConfig.hpp b/src/libslic3r/PrintConfig.hpp
index e07915ae5..44f0f5536 100644
--- a/src/libslic3r/PrintConfig.hpp
+++ b/src/libslic3r/PrintConfig.hpp
@@ -83,8 +83,11 @@ enum InfillPattern : uint8_t{
     ipGyroid, ipHilbertCurve, ipArchimedeanChords, ipOctagramSpiral,
     ipAdaptiveCubic, ipSupportCubic, 
     ipSmooth, ipSmoothHilbert, ipSmoothTriple,
-    ipRectiWithPerimeter, ipConcentricGapFill, ipScatteredRectilinear, ipSawtooth, ipRectilinearWGapFill, 
+    ipRectiWithPerimeter, ipConcentricGapFill, ipScatteredRectilinear, 
+    ipSawtooth,
+    ipRectilinearWGapFill,
     ipMonotonic,
+    ipMonotonicWGapFill,
     ipCount
 };
 
@@ -229,7 +232,7 @@ template<> inline const t_config_enum_values& ConfigOptionEnum<InfillPattern>::g
     static t_config_enum_values keys_map;
     if (keys_map.empty()) {
         keys_map["rectilinear"]         = ipRectilinear;
-        keys_map["monotonic"]          = ipMonotonic;
+        keys_map["monotonic"]           = ipMonotonic;
         keys_map["grid"]                = ipGrid;
         keys_map["triangles"]           = ipTriangles;
         keys_map["stars"]               = ipStars;
@@ -249,6 +252,7 @@ template<> inline const t_config_enum_values& ConfigOptionEnum<InfillPattern>::g
         keys_map["rectiwithperimeter"]  = ipRectiWithPerimeter;
         keys_map["scatteredrectilinear"]= ipScatteredRectilinear;
         keys_map["rectilineargapfill"]  = ipRectilinearWGapFill;
+        keys_map["monotonicgapfill"]    = ipMonotonicWGapFill;
         keys_map["sawtooth"]            = ipSawtooth;
         keys_map["adaptivecubic"]       = ipAdaptiveCubic;
         keys_map["supportcubic"]        = ipSupportCubic;