diff --git a/Extensions/TextObject/TextObject.cpp b/Extensions/TextObject/TextObject.cpp
index 5a1f63268d..cc9999b583 100644
--- a/Extensions/TextObject/TextObject.cpp
+++ b/Extensions/TextObject/TextObject.cpp
@@ -274,7 +274,7 @@ bool RuntimeTextObject::ChangeProperty(std::size_t propertyNb,
   } else if (propertyNb == 1) {
     ChangeFont(newValue);
   } else if (propertyNb == 2) {
-    SetCharacterSize(newValue.To<int>());
+    SetCharacterSize(std::max(1, newValue.To<int>()));
   } else if (propertyNb == 3) {
     gd::String r, gb, g, b;
     {
@@ -297,7 +297,7 @@ bool RuntimeTextObject::ChangeProperty(std::size_t propertyNb,
 
     SetColor(r.To<int>(), g.To<int>(), b.To<int>());
   } else if (propertyNb == 4) {
-    SetOpacity(newValue.To<float>());
+    SetOpacity(std::min(std::max(0.0f, newValue.To<float>()), 255.0f));
   } else if (propertyNb == 5) {
     SetSmooth(!(newValue == _("No")));
   }
diff --git a/Extensions/TextObject/textruntimeobject.js b/Extensions/TextObject/textruntimeobject.js
index 303428e203..f52a6dd6ca 100644
--- a/Extensions/TextObject/textruntimeobject.js
+++ b/Extensions/TextObject/textruntimeobject.js
@@ -14,7 +14,7 @@ gdjs.TextRuntimeObject = function(runtimeScene, objectData)
 {
     gdjs.RuntimeObject.call(this, runtimeScene, objectData);
 
-    this._characterSize = objectData.characterSize;
+    this._characterSize = Math.max(1, objectData.characterSize);
     this._fontName = objectData.font;
     this._bold = objectData.bold;
     this._italic = objectData.italic;
diff --git a/newIDE/app/src/ObjectsRendering/Renderers/RenderedTextInstance.js b/newIDE/app/src/ObjectsRendering/Renderers/RenderedTextInstance.js
index 187346b0fe..1205cb81c6 100644
--- a/newIDE/app/src/ObjectsRendering/Renderers/RenderedTextInstance.js
+++ b/newIDE/app/src/ObjectsRendering/Renderers/RenderedTextInstance.js
@@ -87,7 +87,7 @@ RenderedTextInstance.prototype.update = function() {
 
   if (this._styleFontDirty) {
     this._pixiObject.style.fontFamily = this._fontFamily || 'Arial';
-    this._pixiObject.style.fontSize = this._characterSize + 'px';
+    this._pixiObject.style.fontSize = Math.max(1, this._characterSize) + 'px';
     this._pixiObject.style.fontStyle = this._isItalic ? 'italic' : 'normal';
     this._pixiObject.style.fontWeight = this._isBold ? 'bold' : 'normal';
     this._pixiObject.style.wordWrap = this._wrapping;