diff --git a/world.c b/world.c
index a73df94..146bf9c 100644
--- a/world.c
+++ b/world.c
@@ -54,7 +54,7 @@ static INLINE void drawface_triangle_fan(const ps1bsp_face_t *face, SVECTOR *vec
 {
     int p;
 
-    if (!mem_checkprim(sizeof(POLY_G3), face->numFaceVertices))
+    if (!mem_checkprim(sizeof(POLY_G3), face->numFaceVertices - 2))
         return;
 
     // Draw the face as a triangle fan
@@ -94,7 +94,8 @@ static INLINE void drawface_triangle_strip(const ps1bsp_face_t *face, SVECTOR *v
 {
     int p;
 
-    if (!mem_checkprim(sizeof(POLY_G3), face->numFaceVertices))
+    u_char numTris = face->numFaceVertices - 2;
+    if (!mem_checkprim(sizeof(POLY_G3), numTris))
         return;
 
     // Draw the face as a triangle strip
@@ -105,7 +106,6 @@ static INLINE void drawface_triangle_strip(const ps1bsp_face_t *face, SVECTOR *v
 
     v2 = head++;    // Initialize first vertex to index 0 and set head to index 1
 
-    u_char numTris = face->numFaceVertices - 2;
     for (u_char triIdx = 0; triIdx < numTris; ++triIdx)
     {
         if (reverse ^= 1)
@@ -150,7 +150,8 @@ static INLINE void drawface_quad_strip(const ps1bsp_face_t *face, SVECTOR *vecs)
 {
     int p;
 
-    if (!mem_checkprim(sizeof(POLY_G4), face->numFaceVertices))
+    u_char numQuads = (face->numFaceVertices - 1) / 2;
+    if (!mem_checkprim(sizeof(POLY_G4), numQuads))
         return;
 
     // Draw the face as a quad strip
@@ -163,7 +164,6 @@ static INLINE void drawface_quad_strip(const ps1bsp_face_t *face, SVECTOR *vecs)
     v3 = head++;
 
     // Normally a quad strip would have (N-2)/2 quads, but we might end up with a sole triangle at the end which will be drawn as a collapsed quad
-    u_char numQuads = (face->numFaceVertices - 1) / 2;
     for (u_char quadIdx = 0; quadIdx < numQuads; ++quadIdx)
     {
         v0 = v2;
@@ -208,7 +208,8 @@ static INLINE void drawface_quad_strip_tex(const ps1bsp_face_t *face, STVECTOR *
 {
     int p;
 
-    if (!mem_checkprim(sizeof(POLY_GT4), face->numFaceVertices))
+    u_char numQuads = (face->numFaceVertices - 1) / 2;
+    if (!mem_checkprim(sizeof(POLY_GT4), numQuads))
         return;
 
     // Draw the face as a quad strip
@@ -221,7 +222,6 @@ static INLINE void drawface_quad_strip_tex(const ps1bsp_face_t *face, STVECTOR *
     v3 = head++;
 
     // Normally a quad strip would have (N-2)/2 quads, but we might end up with a sole triangle at the end which will be drawn as a collapsed quad
-    u_char numQuads = (face->numFaceVertices - 1) / 2;
     for (u_char quadIdx = 0; quadIdx < numQuads; ++quadIdx)
     {
         v0 = v2;