diff --git a/lib/linguist/languages.yml b/lib/linguist/languages.yml
index 454a439d..bef32f56 100644
--- a/lib/linguist/languages.yml
+++ b/lib/linguist/languages.yml
@@ -304,9 +304,21 @@ FORTRAN:
   primary_extension: .f90
   extensions:
   - .F
+  - .F77
   - .F90
+  - .F95
+  - .F03
+  - .F08
+  - .FOR
+  - .FPP
   - .f
+  - .f77
   - .f90
+  - .f95
+  - .f03
+  - .f08
+  - .for
+  - .fpp
 
 Factor:
   type: programming