diff --git a/src/Fl.cxx b/src/Fl.cxx
index de2b869e1..232d4bb6b 100644
--- a/src/Fl.cxx
+++ b/src/Fl.cxx
@@ -1234,7 +1234,7 @@ Fl_Window::~Fl_Window() {
 // FL_SHOW and FL_HIDE are called whenever the visibility of this widget
 // or any parent changes.  We must correctly map/unmap the system's window.
 
-// For top-level windows it is assummed the window has already been
+// For top-level windows it is assumed the window has already been
 // mapped or unmapped!!!  This is because this should only happen when
 // Fl_Window::show() or Fl_Window::hide() is called, or in response to
 // iconize/deiconize events from the system.
diff --git a/src/Fl_Gl_Choice.cxx b/src/Fl_Gl_Choice.cxx
index 66e7f115e..041d4e2aa 100644
--- a/src/Fl_Gl_Choice.cxx
+++ b/src/Fl_Gl_Choice.cxx
@@ -46,7 +46,7 @@ void fl_save_dc(HWND, HDC);
 
 static Fl_Gl_Choice *first;
 
-// this assummes one of the two arguments is zero:
+// this assumes one of the two arguments is zero:
 // We keep the list system in Win32 to stay compatible and interpret
 // the list later...
 Fl_Gl_Choice *Fl_Gl_Choice::find(int m, const int *alistp) {
diff --git a/src/Fl_Menu.cxx b/src/Fl_Menu.cxx
index a4302e958..44f78673a 100644
--- a/src/Fl_Menu.cxx
+++ b/src/Fl_Menu.cxx
@@ -423,7 +423,7 @@ void menuwindow::drawentry(const Fl_Menu_Item* m, int n, int eraseit) {
 
   m->draw(xx, yy, ww, hh, button, n==selected);
 
-  // the shortcuts and arrows assumme fl_color() was left set by draw():
+  // the shortcuts and arrows assume fl_color() was left set by draw():
   if (m->submenu()) {
     int sz = (hh-7)&-2;
     int y1 = yy+(hh-sz)/2;
diff --git a/src/Fl_Menu_add.cxx b/src/Fl_Menu_add.cxx
index bf6e54dd4..e9cf50893 100644
--- a/src/Fl_Menu_add.cxx
+++ b/src/Fl_Menu_add.cxx
@@ -120,7 +120,7 @@ int Fl_Menu_Item::add(
   // split at slashes to make submenus:
   for (;;) {
 
-    // leading slash makes us assumme it is a filename:
+    // leading slash makes us assume it is a filename:
     if (*mytext == '/') {item = mytext; break;}
 
     // leading underscore causes divider line:
diff --git a/src/Fl_Tooltip.cxx b/src/Fl_Tooltip.cxx
index 3fd24f1b3..6c6ab4226 100644
--- a/src/Fl_Tooltip.cxx
+++ b/src/Fl_Tooltip.cxx
@@ -209,7 +209,7 @@ void Fl_Tooltip::exit_(Fl_Widget *w) {
 
 // Get ready to display a tooltip. The widget and the xywh box inside
 // it define an area the tooltip is for, this along with the current
-// mouse position places the tooltip (the mouse is assummed to point
+// mouse position places the tooltip (the mouse is assumed to point
 // inside or near the box).
 /**
   You may be able to use this to provide tooltips for internal pieces
diff --git a/src/Fl_arg.cxx b/src/Fl_arg.cxx
index 4c537e320..415cf2f85 100644
--- a/src/Fl_arg.cxx
+++ b/src/Fl_arg.cxx
@@ -336,7 +336,7 @@ void Fl_Window::show(int argc, char **argv) {
       //  if (mh > gh) gh = mh;
       Fl_Widget *r = resizable();
       if (!r) resizable(this);
-      // for WIN32 we assumme window is not mapped yet:
+      // for WIN32 we assume window is not mapped yet:
       if (fl & (XValue | YValue))
 	x(-1), resize(gx,gy,gw,gh);
       else
diff --git a/src/Fl_x.cxx b/src/Fl_x.cxx
index f8df4d257..46ef72aa4 100644
--- a/src/Fl_x.cxx
+++ b/src/Fl_x.cxx
@@ -1447,7 +1447,7 @@ void Fl_X::make_xid(Fl_Window* win, XVisualInfo *visual, Colormap colormap)
 
     if (win->border()) {
       // ensure border is on screen:
-      // (assumme extremely minimal dimensions for this border)
+      // (assume extremely minimal dimensions for this border)
       const int top = 20;
       const int left = 1;
       const int right = 1;
@@ -1696,7 +1696,7 @@ void Fl_Window::label(const char *name,const char *iname) {
 //
 // On XFree86 (and prehaps all X's) this has a problem if the window
 // is resized while a save-behind window is atop it.  The previous
-// contents are restored to the area, but this assummes the area
+// contents are restored to the area, but this assumes the area
 // is cleared to background color.  So this is disabled in this version.
 // Fl_Window *fl_boxcheat;
 static inline int can_boxcheat(uchar b) {return (b==1 || (b&2) && b<=15);}
diff --git a/src/fl_color.cxx b/src/fl_color.cxx
index 6e4a708f4..94afa5547 100644
--- a/src/fl_color.cxx
+++ b/src/fl_color.cxx
@@ -302,7 +302,7 @@ ulong fl_xpixel(Fl_Color i) {
     xmap.pixel = p.pixel;
   } else {
     // However, if that XAllocColor fails, I have to give up and
-    // assumme the pixel is ok for the duration of the program.  This
+    // assume the pixel is ok for the duration of the program.  This
     // is due to bugs (?) in the Solaris X and some X terminals
     // where XAllocColor *always* fails when the colormap is full,
     // even if we ask for a color already in it...
diff --git a/src/fl_scroll_area.cxx b/src/fl_scroll_area.cxx
index 4a361c37a..e87cba026 100644
--- a/src/fl_scroll_area.cxx
+++ b/src/fl_scroll_area.cxx
@@ -91,7 +91,7 @@ void fl_scroll(int X, int Y, int W, int H, int dx, int dy,
   for (;;) {
     XEvent e; XWindowEvent(fl_display, fl_window, ExposureMask, &e);
     if (e.type == NoExpose) break;
-    // otherwise assumme it is a GraphicsExpose event:
+    // otherwise assume it is a GraphicsExpose event:
     draw_area(data, e.xexpose.x, e.xexpose.y,
 	      e.xexpose.width, e.xexpose.height);
     if (!e.xgraphicsexpose.count) break;
diff --git a/src/fl_set_fonts_x.cxx b/src/fl_set_fonts_x.cxx
index 6c5dcc0e0..bf9f7b403 100644
--- a/src/fl_set_fonts_x.cxx
+++ b/src/fl_set_fonts_x.cxx
@@ -191,7 +191,7 @@ static int ultrasort(const void *aa, const void *bb) {
     if (*b != '-') return -1;
   }
 
-  // skip the foundry (assumme equal):
+  // skip the foundry (assume equal):
   for (a++; *a && *a++!='-';);
   for (b++; *b && *b++!='-';);
 
diff --git a/src/fl_utf.c b/src/fl_utf.c
index 18355f428..327cbe946 100644
--- a/src/fl_utf.c
+++ b/src/fl_utf.c
@@ -211,8 +211,8 @@ unsigned fl_utf8decode(const char* p, const char* end, int* len)
   \e start is the start of the string and is used to limit the
   backwards search for the start of a utf8 character.
 
-  \e end is the end of the string and is assummed to be a break
-  between characters. It is assummed to be greater than p.
+  \e end is the end of the string and is assumed to be a break
+  between characters. It is assumed to be greater than p.
 
   This function is for moving a pointer that was jumped to the
   middle of a string, such as when doing a binary search for
@@ -247,8 +247,8 @@ const char* fl_utf8fwd(const char* p, const char* start, const char* end)
   \e start is the start of the string and is used to limit the
   backwards search for the start of a UTF-8 character.
 
-  \e end is the end of the string and is assummed to be a break
-  between characters. It is assummed to be greater than p.
+  \e end is the end of the string and is assumed to be a break
+  between characters. It is assumed to be greater than p.
 
   If you wish to decrement a UTF-8 pointer, pass p-1 to this.
 */
@@ -655,7 +655,7 @@ int fl_utf8locale(void) {
     ret = GetACP() == CP_UTF8;
 #else
     char* s;
-    ret = 1; /* assumme UTF-8 if no locale */
+    ret = 1; /* assume UTF-8 if no locale */
     if (((s = getenv("LC_CTYPE")) && *s) ||
 	((s = getenv("LC_ALL"))   && *s) ||
 	((s = getenv("LANG"))     && *s)) {
diff --git a/src/forms_fselect.cxx b/src/forms_fselect.cxx
index a0ee32131..928aa601d 100644
--- a/src/forms_fselect.cxx
+++ b/src/forms_fselect.cxx
@@ -31,7 +31,7 @@
 #include "flstring.h"
 
 static char fl_directory[1024];
-static const char *fl_pattern;  // assummed passed value is static
+static const char *fl_pattern;  // assumed passed value is static
 static char fl_filename[1024];
 
 char* fl_show_file_selector(const char *message,const char *dir,