diff --git a/src/App/PropertyStandard.cpp b/src/App/PropertyStandard.cpp
index dfc22f2e5a..7ff3b24f0b 100644
--- a/src/App/PropertyStandard.cpp
+++ b/src/App/PropertyStandard.cpp
@@ -2229,7 +2229,7 @@ PyObject *PropertyBoolList::getPyObject(void)
 
 void PropertyBoolList::setPyObject(PyObject *value)
 {
-    // string is also a sequence and must be be treated differently
+    // string is also a sequence and must be treated differently
     std::string str;
     if (PyUnicode_Check(value)) {
 #if PY_MAJOR_VERSION >= 3
diff --git a/src/Gui/BlenderNavigationStyle.cpp b/src/Gui/BlenderNavigationStyle.cpp
index c18b776e4e..7d7034d555 100644
--- a/src/Gui/BlenderNavigationStyle.cpp
+++ b/src/Gui/BlenderNavigationStyle.cpp
@@ -375,7 +375,7 @@ SbBool BlenderNavigationStyle::processSoEvent(const SoEvent * const ev)
     }
 
     // If for dragging the buttons 1 and 3 are pressed
-    // but then button 3 is relaesed we shouldn't switch
+    // but then button 3 is released we shouldn't switch
     // into selection mode.
     if (this->button1down && this->button3down)
         this->lockButton1 = true;
diff --git a/src/Gui/CADNavigationStyle.cpp b/src/Gui/CADNavigationStyle.cpp
index 12e4e7e24c..d6ac60433f 100644
--- a/src/Gui/CADNavigationStyle.cpp
+++ b/src/Gui/CADNavigationStyle.cpp
@@ -446,7 +446,7 @@ SbBool CADNavigationStyle::processSoEvent(const SoEvent * const ev)
     }
 
     // If for dragging the buttons 1 and 3 are pressed
-    // but then button 3 is relaesed we shouldn't switch
+    // but then button 3 is released we shouldn't switch
     // into selection mode.
     if (this->button1down && this->button3down)
         this->lockButton1 = true;
diff --git a/src/Gui/RevitNavigationStyle.cpp b/src/Gui/RevitNavigationStyle.cpp
index 27cd2e0a24..8f5fddb821 100644
--- a/src/Gui/RevitNavigationStyle.cpp
+++ b/src/Gui/RevitNavigationStyle.cpp
@@ -375,7 +375,7 @@ SbBool RevitNavigationStyle::processSoEvent(const SoEvent * const ev)
     }
 
     // If for dragging the buttons 1 and 3 are pressed
-    // but then button 3 is relaesed we shouldn't switch
+    // but then button 3 is released we shouldn't switch
     // into selection mode.
     if (this->button1down && this->button3down)
         this->lockButton1 = true;
diff --git a/src/Gui/SoFCBoundingBox.h b/src/Gui/SoFCBoundingBox.h
index a7903a3430..34ba8f1e88 100644
--- a/src/Gui/SoFCBoundingBox.h
+++ b/src/Gui/SoFCBoundingBox.h
@@ -79,7 +79,7 @@ private:
 };
 
 /**
- * This is a special group node which be be defined to ignore bounding box actions.
+ * This is a special group node which must be defined to ignore bounding box actions.
  * @author Werner Mayer
  */
 class GuiExport SoSkipBoundingGroup : public SoGroup {