diff --git a/polymer/eduke32/source/lunatic/geom.lua b/polymer/eduke32/source/lunatic/geom.lua
index 03c6b1a09..fb95ce153 100644
--- a/polymer/eduke32/source/lunatic/geom.lua
+++ b/polymer/eduke32/source/lunatic/geom.lua
@@ -133,19 +133,35 @@ local vec3_mt = {
     },
 }
 
+ffi.metatype(dvec2_t, vec2_mt)
+ffi.metatype(dvec3_t, vec3_mt)
+
 -- VEC2 user data constructor.
---  * vec2(<table>), <table> should be indexable with "x" and "y"
---  * vec2(x, y), assuming that x and y are numbers
-vec2 = ffi.metatype(dvec2_t, vec2_mt)
-vec3 = ffi.metatype(dvec3_t, vec3_mt)
+--  * vec2([x [, y]]), assuming that x and y are numbers. Vacant positions are
+--    assumed to be 0.
+--  * vec2(<compound>), <compound> can be anything indexable with "x" and "y"
+function vec2(...)
+    local x, y = ...
+    if (type(x)=="number" or x==nil) then
+        return dvec2_t(...)
+    else
+        return dvec2_t(x.x, x.y)
+    end
+end
 
-ivec3 = ffi.metatype("vec3_t", vec3_mt)
+-- VEC3 user data constructor.
+--  Analogous to VEC2.
+function vec3(...)
+    local x, y, z = ...
+    if (type(x)=="number" or x==nil) then
+        return dvec3_t(...)
+    else
+        return dvec3_t(x.x, x.y, x.z)
+    end
+end
 
--- Returns a vec2 from anything indexable with "x" and "y"
--- (vec2(t) works if t is such a table, but not if it's a vec2 or a cdata of
--- different type)
-function tovec2(t) return dvec2_t(t.x, t.y) end
-function tovec3(t) return dvec3_t(t.x, t.y, t.z) end
+-- TODO: make a constructor like VEC3?
+ivec3 = ffi.metatype(ivec3_t, vec3_mt)
 
 
 -- Two-element vector cross product.
@@ -168,11 +184,11 @@ function intersect(a,v, b,w, retpoint_p)
     local vxw = cross2(v,w)
 
     if (vxw ~= 0) then
-        local btoa = tovec2(a)-tovec2(b)
+        local btoa = vec2(a) - vec2(b)
         local cv, cw = cross2(w, btoa)/vxw, cross2(v, btoa)/vxw
 
         if (retpoint_p) then
-            return tovec2(a)+cv*tovec2(v)
+            return vec2(a) + cv*vec2(v)
         else
             return cv, cw
         end
diff --git a/polymer/eduke32/source/lunatic/m32/randwalk.lua b/polymer/eduke32/source/lunatic/m32/randwalk.lua
index 01834f2b7..5b36688fd 100644
--- a/polymer/eduke32/source/lunatic/m32/randwalk.lua
+++ b/polymer/eduke32/source/lunatic/m32/randwalk.lua
@@ -33,7 +33,7 @@ function randwalk(N, spritenum, minlen, maxlen, randofs, funci, logfn)
     local times = {}
     local successp = {}
 
-    local pos = geom.tovec3(sprite[spritenum])
+    local pos = geom.vec3(sprite[spritenum])
     local sectnum = sprite[spritenum].sectnum
 
     for i=1,N do
diff --git a/polymer/eduke32/source/lunatic/test.elua b/polymer/eduke32/source/lunatic/test.elua
index 45af19214..891d1d043 100644
--- a/polymer/eduke32/source/lunatic/test.elua
+++ b/polymer/eduke32/source/lunatic/test.elua
@@ -381,6 +381,9 @@ gameactor
         -- NOTE: __add metamethod is called because of the RHS:
         local v = spr + geom.vec3(r(-d,d), r(-d,d))
         spr:setpos(v)
+
+        -- Test vec3 constructor with cdata.
+        local tempvec = geom.vec3(player[0].pos)
     end
 }
 
diff --git a/polymer/eduke32/source/lunatic/xmath.lua b/polymer/eduke32/source/lunatic/xmath.lua
index 0d1d958a3..83823241a 100644
--- a/polymer/eduke32/source/lunatic/xmath.lua
+++ b/polymer/eduke32/source/lunatic/xmath.lua
@@ -104,7 +104,7 @@ end
 -- XXX: passing mixed vec2/vec3 is problematic. Get rid of geom.vec2?
 -- <ang>: BUILD angle (0-2047 based)
 function rotate(pos, pivot, ang)
-    local p = geom.tovec3(pos)-pivot
+    local p = geom.vec3(pos)-pivot
     local c, s = cosb(ang), sinb(ang)
     local x, y = p.x, p.y
     p.x = pivot.x + (c*x - s*y)