diff --git a/rtdata/languages/default b/rtdata/languages/default
index 2c012d9c2..69cc6adc3 100644
--- a/rtdata/languages/default
+++ b/rtdata/languages/default
@@ -3321,6 +3321,7 @@ TP_PCVIGNETTE_ROUNDNESS_TOOLTIP;Roundness:\n0 = rectangle,\n50 = fitted ellipse,
 TP_PCVIGNETTE_STRENGTH;Strength
 TP_PCVIGNETTE_STRENGTH_TOOLTIP;Filter strength in stops (reached in corners).
 TP_PDSHARPENING_LABEL;Capture Sharpening
+TP_PERSPECTIVE_CONTROL_LINE_APPLY_INVALID_TOOLTIP;At least two horizontal or two vertical control lines required.
 TP_PERSPECTIVE_CAMERA_CROP_FACTOR;Crop factor
 TP_PERSPECTIVE_CAMERA_FOCAL_LENGTH;Focal length
 TP_PERSPECTIVE_CAMERA_FRAME;Correction
diff --git a/rtgui/controllines.cc b/rtgui/controllines.cc
index 14454e2ef..65106f375 100644
--- a/rtgui/controllines.cc
+++ b/rtgui/controllines.cc
@@ -84,6 +84,7 @@ ControlLineManager::ControlLineManager():
     draw_mode(false),
     drawing_line(false),
     edited(false),
+    horizontalCount(0), verticalCount(0),
     prev_obj(-1),
     selected_object(-1)
 {
@@ -127,11 +128,21 @@ void ControlLineManager::setDrawMode(bool draw)
     draw_mode = draw;
 }
 
-size_t ControlLineManager::size(void) const
+std::size_t ControlLineManager::size() const
 {
     return control_lines.size();
 }
 
+std::size_t ControlLineManager::getHorizontalCount() const
+{
+    return horizontalCount;
+}
+
+std::size_t ControlLineManager::getVerticalCount() const
+{
+    return verticalCount;
+}
+
 bool ControlLineManager::button1Pressed(int modifierKey)
 {
     EditDataProvider* dataProvider = getEditProvider();
@@ -214,9 +225,13 @@ bool ControlLineManager::pick1(bool picked)
     if (line.type == rtengine::ControlLine::HORIZONTAL) {
         line.icon = line.icon_v;
         line.type = rtengine::ControlLine::VERTICAL;
+        horizontalCount--;
+        verticalCount++;
     } else if (line.type == rtengine::ControlLine::VERTICAL) {
         line.icon = line.icon_h;
         line.type = rtengine::ControlLine::HORIZONTAL;
+        horizontalCount++;
+        verticalCount--;
     }
 
     visibleGeometry[mouseOverIdToVisibleId(object_id)] = line.icon.get();
@@ -491,6 +506,11 @@ void ControlLineManager::addLine(Coord begin, Coord end,
     EditSubscriber::mouseOverGeometry.push_back(control_line->end.get());
 
     control_lines.push_back(std::move(control_line));
+    if (type == rtengine::ControlLine::HORIZONTAL) {
+        horizontalCount++;
+    } else {
+        verticalCount++;
+    }
 }
 
 void ControlLineManager::autoSetLineType(int object_id)
@@ -523,6 +543,13 @@ void ControlLineManager::autoSetLineType(int object_id)
     if (type != line.type) { // Need to update line type.
         line.type = type;
         line.icon = icon;
+        if (type == rtengine::ControlLine::HORIZONTAL) {
+            horizontalCount++;
+            verticalCount--;
+        } else {
+            horizontalCount--;
+            verticalCount++;
+        }
         visibleGeometry[line_id * ::ControlLine::OBJECT_COUNT
 + VISIBLE_OBJECT_COUNT + ::ControlLine::ICON] =
             line.icon.get();
@@ -535,13 +562,14 @@ void ControlLineManager::removeAll(void)
     mouseOverGeometry.erase(mouseOverGeometry.begin() + MO_OBJECT_COUNT,
                             mouseOverGeometry.end());
     control_lines.clear();
+    horizontalCount = verticalCount = 0;
     prev_obj = -1;
     selected_object = -1;
     edited = true;
     callbacks->lineChanged();
 }
 
-void ControlLineManager::removeLine(size_t line_id)
+void ControlLineManager::removeLine(std::size_t line_id)
 {
     if (line_id >= control_lines.size()) {
         return;
@@ -556,6 +584,11 @@ void ControlLineManager::removeLine(size_t line_id)
         mouseOverGeometry.begin() + ::ControlLine::OBJECT_COUNT * line_id + MO_OBJECT_COUNT,
         mouseOverGeometry.begin() + ::ControlLine::OBJECT_COUNT * line_id + MO_OBJECT_COUNT + ::ControlLine::OBJECT_COUNT
     );
+    if (control_lines[line_id]->type == rtengine::ControlLine::HORIZONTAL) {
+        horizontalCount--;
+    } else {
+        verticalCount--;
+    }
     control_lines.erase(control_lines.begin() + line_id);
 
     edited = true;
diff --git a/rtgui/controllines.h b/rtgui/controllines.h
index a05fb8b00..9e850da1c 100644
--- a/rtgui/controllines.h
+++ b/rtgui/controllines.h
@@ -59,6 +59,7 @@ protected:
     bool draw_mode;
     bool drawing_line;
     bool edited;
+    std::size_t horizontalCount, verticalCount;
     Cairo::RefPtr<RTSurface> line_icon_h, line_icon_v;
     Cairo::RefPtr<RTSurface> line_icon_h_prelight, line_icon_v_prelight;
     int prev_obj;
@@ -74,7 +75,7 @@ protected:
      * line, inclusive, the line type is set to vertical. Otherwise, horizontal.
      */
     void autoSetLineType(int object_id);
-    void removeLine(size_t line_id);
+    void removeLine(std::size_t line_id);
 
 public:
     class Callbacks
@@ -94,6 +95,10 @@ public:
     ~ControlLineManager();
 
     bool getEdited(void) const;
+    /** Returns the number of horizontal control lines. */
+    std::size_t getHorizontalCount() const;
+    /** Returns the number of vertical control lines. */
+    std::size_t getVerticalCount() const;
     /** Release anything that is currently being dragged. */
     void releaseEdit(void);
     void removeAll(void);
@@ -105,7 +110,7 @@ public:
     void setEditProvider(EditDataProvider* provider);
     void setLines(const std::vector<rtengine::ControlLine>& lines);
     /** Returns the number of lines. */
-    size_t size(void) const;
+    std::size_t size() const;
     /**
      * Allocates a new array and populates it with copies of the control lines.
      */
diff --git a/rtgui/perspective.cc b/rtgui/perspective.cc
index fb4797ae4..d06243524 100644
--- a/rtgui/perspective.cc
+++ b/rtgui/perspective.cc
@@ -351,6 +351,8 @@ void PerspCorrection::read (const ProcParams* pp, const ParamsEdited* pedited)
         method->set_active (1);
     }
 
+    updateApplyDeleteButtons();
+
     enableListener ();
 }
 
@@ -517,22 +519,16 @@ void PerspCorrection::applyControlLines(void)
     }
 
     std::vector<rtengine::ControlLine> control_lines;
-    int h_count = 0, v_count = 0;
     double rot = camera_roll->getValue();
     double pitch = camera_pitch->getValue();
     double yaw = camera_yaw->getValue();
 
     lines->toControlLines(control_lines);
 
-    for (unsigned int i = 0; i < lines->size(); i++) {
-        if (control_lines[i].type == rtengine::ControlLine::HORIZONTAL) {
-            h_count++;
-        } else if (control_lines[i].type == rtengine::ControlLine::VERTICAL) {
-            v_count++;
-        }
-    }
-    lens_geom_listener->autoPerspRequested(v_count > 1, h_count > 1, rot, pitch,
-            yaw, &control_lines);
+    lens_geom_listener->autoPerspRequested(
+            lines->getVerticalCount() >= MIN_VERT_LINES,
+            lines->getHorizontalCount() >= MIN_HORIZ_LINES,
+            rot, pitch, yaw, &control_lines);
 
     disableListener();
     camera_pitch->setValue(pitch);
@@ -739,11 +735,29 @@ void PerspCorrection::setEditProvider(EditDataProvider* provider)
 
 void PerspCorrection::lineChanged(void)
 {
+    updateApplyDeleteButtons();
+
     if (listener) {
         listener->panelChanged(EvPerspControlLines, M("HISTORY_CHANGED"));
     }
 }
 
+void PerspCorrection::updateApplyDeleteButtons()
+{
+    if (batchMode) {
+        return;
+    }
+
+    bool edit_mode = lines_button_edit->get_active();
+    bool enough_lines = lines->getHorizontalCount() >= MIN_HORIZ_LINES || lines->getVerticalCount() >= MIN_VERT_LINES;
+    const auto tooltip = M("GENERAL_APPLY")
+        + ((edit_mode && !enough_lines) ? "\n\n" + M("TP_PERSPECTIVE_CONTROL_LINE_APPLY_INVALID_TOOLTIP") : "");
+
+    lines_button_apply->set_sensitive(edit_mode && enough_lines);
+    lines_button_apply->set_tooltip_text(tooltip);
+    lines_button_erase->set_sensitive(edit_mode && lines->size() > 0);
+}
+
 void PerspCorrection::linesApplyButtonPressed(void)
 {
     if (method->get_active_row_number() == 1) {
@@ -785,6 +799,7 @@ void PerspCorrection::linesEditButtonPressed(void)
             panel_listener->controlLineEditModeChanged(false);
         }
     }
+    updateApplyDeleteButtons();
 }
 
 void PerspCorrection::linesEraseButtonPressed(void)
@@ -796,6 +811,8 @@ void PerspCorrection::requestApplyControlLines(void)
 {
     if (lines_button_apply->is_sensitive()) {
         linesApplyButtonPressed();
+    } else if (lines_button_edit->get_active()) {
+        lines_button_edit->set_active(false);
     }
 }
 
diff --git a/rtgui/perspective.h b/rtgui/perspective.h
index 6f4a4ff52..404b02010 100644
--- a/rtgui/perspective.h
+++ b/rtgui/perspective.h
@@ -96,9 +96,15 @@ protected:
     void tweakParams(rtengine::procparams::ProcParams &pparams) override;
     void setCamBasedEventsActive (bool active = true);
     void setFocalLengthValue (const rtengine::procparams::ProcParams* pparams, const rtengine::FramesMetaData* metadata);
+    void updateApplyDeleteButtons();
 
 public:
 
+    /** Minimum number of horizontal lines for horizontal/full correction. */
+    static constexpr std::size_t MIN_HORIZ_LINES = 2;
+    /** Minimum number of vertical lines for vertical/full correction. */
+    static constexpr std::size_t MIN_VERT_LINES = 2;
+
     PerspCorrection ();
 
     void read           (const rtengine::procparams::ProcParams* pp, const ParamsEdited* pedited = nullptr) override;