diff --git a/lib/linguist/languages.yml b/lib/linguist/languages.yml
index c6cd85a3..a253fde8 100644
--- a/lib/linguist/languages.yml
+++ b/lib/linguist/languages.yml
@@ -299,7 +299,6 @@ Darcs Patch:
 Dart:
   type: programming
   lexer: Dart
-  primary_extension: .dart
   extensions:
   - .dart
 
@@ -624,7 +623,6 @@ JavaScript:
 Julia:
   type: programming
   lexer: Julia
-  primary_extension: .jl
   extensions:
   - .jl
 
@@ -658,14 +656,12 @@ Literate Haskell:
 
 Logtalk:
   type: programming
-  primary_extension: .lgt
   extensions:
   - .lgt
 
 Lua:
   type: programming
   ace_mode: lua
-  primary_extension: .lua
   extensions:
   - .lua
   - .nse
@@ -1001,7 +997,6 @@ Ruby:
 Rust:
   type: programming
   lexer: Text only
-  primary_extension: .rs
   extensions:
   - .rs
 
@@ -1023,7 +1018,6 @@ Sage:
   type: programming
   lexer: Python
   group: Python
-  primary_extension: .sage
   extensions:
   - .sage
 
@@ -1163,7 +1157,6 @@ Textile:
 Turing:
   type: programming
   lexer: Text only
-  primary_extension: .t
   extensions:
   - .t
   - .tu
@@ -1178,7 +1171,6 @@ Twig:
 VHDL:
   type: programming
   lexer: vhdl
-  primary_extension: .vhd
   extensions:
   - .vhd
   - .vhdl