diff --git a/lib/symbols b/lib/symbols
index 2cfe9ee739..f69d28438a 100644
--- a/lib/symbols
+++ b/lib/symbols
@@ -929,6 +929,23 @@ bmod               lyxblacktext  0   0 func     x
 pmod               lyxblacktext  0   0 func     x
 
 
+# mathtools.sty
+# no automatic loading without file format change
+\def\vcentcolon{\kern4mu:\kern3mu}
+\def\dblcolon{\vcentcolon\kern-8mu\vcentcolon}
+\def\coloneqq{\vcentcolon\kern-7mu=}
+\def\Coloneqq{\dblcolon\kern-7mu=}
+\def\coloneq{\vcentcolon\kern-7mu-}
+\def\Coloneq{\dblcolon\kern-7mu-}
+\def\eqqcolon{=\kern-8mu\vcentcolon}
+\def\Eqqcolon{=\kern-8mu\dblcolon}
+\def\eqcolon{-\kern-8mu\vcentcolon}
+\def\Eqcolon{-\kern-8mu\dblcolon}
+\def\colonapprox{\vcentcolon\kern-7mu\approx}
+\def\Colonapprox{\dblcolon\kern-7mu\approx}
+\def\colonsim{\vcentcolon\kern-7mu\sim}
+\def\Colonsim{\dblcolon\kern-7mu\sim}
+
 
 #
 # pre-defined macros
diff --git a/lib/unicodesymbols b/lib/unicodesymbols
index d033698fa1..305fb25f1d 100644
--- a/lib/unicodesymbols
+++ b/lib/unicodesymbols
@@ -1909,12 +1909,12 @@
 0x2234 ""                         "" "" "\\therefore" "amssymb" # THEREFORE
 0x2235 ""                         "" "" "\\because" "amssymb" # BECAUSE
 #0x2236 ""                         "" "" "" "" # RATIO
-#0x2237 ""                         "" "" "" "" # PROPORTION
+0x2237 ""                         "" "" "" "\\dblcolon" "mathtools" # PROPORTION
 #0x2238 ""                         "" "" "" "" # DOT MINUS
-#0x2239 ""                         "" "" "" "" # EXCESS
+0x2239 ""                         "" "" "" "\\eqcolon" "mathtools" # EXCESS
 #0x223a ""                         "" "" "" "" # GEOMETRIC PROPORTION
 #0x223b ""                         "" "" "" "" # HOMOTHETIC
-#0x223c ""                         "" "" "" "" # TILDE OPERATOR
+0x223c ""                         "" "" "" "\\sim" # TILDE OPERATOR
 #0x223d ""                         "" "" "" "" # REVERSED TILDE
 #0x223e ""                         "" "" "" "" # INVERTED LAZY S
 #0x223f ""                         "" "" "" "" # SINE WAVE
@@ -1938,8 +1938,8 @@
 #0x2251 ""                         "" "" "" "" # GEOMETRICALLY EQUAL TO
 #0x2252 ""                         "" "" "" "" # APPROXIMATELY EQUAL TO OR THE IMAGE OF
 #0x2253 ""                         "" "" "" "" # IMAGE OF OR APPROXIMATELY EQUAL TO
-#0x2254 ""                         "" "" "" "" # COLON EQUALS
-#0x2255 ""                         "" "" "" "" # EQUALS COLON
+0x2254 ""                         "" "" "" "\\coloneqq" "mathtools" # COLON EQUALS
+0x2255 ""                         "" "" "" "\\\eqqcolon" "mathtools"  # EQUALS COLON
 #0x2256 ""                         "" "" "" "" # RING IN EQUAL TO
 #0x2257 ""                         "" "" "" "" # RING EQUAL TO
 #0x2258 ""                         "" "" "" "" # CORRESPONDS TO
diff --git a/src/LaTeXFeatures.cpp b/src/LaTeXFeatures.cpp
index 6f8ce5c9ca..1f66ce5052 100644
--- a/src/LaTeXFeatures.cpp
+++ b/src/LaTeXFeatures.cpp
@@ -575,6 +575,7 @@ char const * simplefeatures[] = {
 	"mathdesign",
 	"mathrsfs",
 	"mathabx",
+	"mathtools",
 	"ascii",
 	"url",
 	"covington",