diff --git a/fortran/test/tf_F90.f90 b/fortran/test/tf_F90.f90
index e820350394..11a047cb6b 100644
--- a/fortran/test/tf_F90.f90
+++ b/fortran/test/tf_F90.f90
@@ -25,6 +25,7 @@
 !
 !*****
 MODULE TH5_MISC_PROVISIONAL
+  IMPLICIT NONE
 
   INTEGER, PARAMETER :: sp = KIND(0.0)
   INTEGER, PARAMETER :: dp = KIND(0.D0)