diff --git a/lib/bind/cua.bind b/lib/bind/cua.bind
index 7487c08a2e..f224af6f8b 100644
--- a/lib/bind/cua.bind
+++ b/lib/bind/cua.bind
@@ -226,7 +226,7 @@ Format 1
 \bind "C-Return"		"newline-insert newline"
 \bind "C-S-Return"		"newline-insert linebreak"
 \bind "C-k"			"line-delete-forward"
-\bind "C-space"			"space-insert protected"
+\bind "C-space"			"command-alternatives space-insert protected ; math-space"
 \bind "nobreakspace"		"space-insert protected"
 \bind "C-M-space"		"space-insert normal"
 \bind "S-C-space"		"space-insert thin"
diff --git a/lib/bind/emacs.bind b/lib/bind/emacs.bind
index d552c15fca..125ffbce87 100644
--- a/lib/bind/emacs.bind
+++ b/lib/bind/emacs.bind
@@ -219,7 +219,7 @@ Format 1
 \bind "C-Return"		"newline-insert newline"
 \bind "C-S-Return"		"newline-insert linebreak"
 \bind "C-S-L"			"specialchar-insert ligature-break"
-\bind "C-space"			"space-insert protected"
+\bind "C-space"			"command-alternatives space-insert protected ; math-space"
 \bind "nobreakspace"		"space-insert protected"
 \bind "C-M-space"		"space-insert normal"
 \bind "S-C-space"		"space-insert thin"
diff --git a/lib/bind/mac.bind b/lib/bind/mac.bind
index 4c59a0cb09..2461a23dec 100644
--- a/lib/bind/mac.bind
+++ b/lib/bind/mac.bind
@@ -345,7 +345,7 @@ Format 1
 \bind "M-Return"                     "break-paragraph inverse"
 \bind "C-Return"                     "newline-insert newline"
 \bind "C-S-Return"                   "newline-insert linebreak"
-\bind "A-space"                      "space-insert protected"
+\bind "A-space"                      "command-alternatives space-insert protected ; math-space"
 \bind "nobreakspace"                 "space-insert protected"
 \bind "C-A-space"                    "space-insert normal"
 \bind "S-A-space"                    "space-insert thin"
diff --git a/lib/bind/xemacs.bind b/lib/bind/xemacs.bind
index 97551aec54..47459464c6 100644
--- a/lib/bind/xemacs.bind
+++ b/lib/bind/xemacs.bind
@@ -225,7 +225,7 @@ Format 1
 \bind "C-Return"		"newline-insert newline"
 \bind "C-S-Return"		"newline-insert linebreak"
 \bind "C-S-L"			"specialchar-insert ligature-break"
-\bind "C-space"			"space-insert protected"
+\bind "C-space"			"command-alternatives space-insert protected ; math-space"
 \bind "nobreakspace"		"space-insert protected"
 \bind "C-M-space"		"space-insert normal"
 \bind "S-C-space"		"space-insert thin"