diff --git a/CMakeLists.txt b/CMakeLists.txt
index 89b278489..ad7dcb99e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -789,6 +789,10 @@ endif (APPLE)
 
 set_source_files_properties (${WSJTX_ICON_FILE} PROPERTIES MACOSX_PACKAGE_LOCATION Resources)
 
+# suppress intransigent compiler diagnostics
+set_source_files_properties (lib/decoder.f90 PROPERTIES COMPILE_FLAGS "-Wno-unused-dummy-argument")
+set_source_files_properties (lib/filbig.f90 PROPERTIES COMPILE_FLAGS "-Wno-aliasing")
+
 if (WSJT_QDEBUG_IN_RELEASE)
   # context info in Qt message handler in release configuration
   set_property (DIRECTORY APPEND PROPERTY
diff --git a/lib/decoder.f90 b/lib/decoder.f90
index f863533ae..d6ecc904a 100644
--- a/lib/decoder.f90
+++ b/lib/decoder.f90
@@ -37,9 +37,8 @@ subroutine multimode_decoder(ipc1,ss,id2,params,nfsample)
   integer*2 id2(NTMAX*12000)
   type(params_block) :: params
   real*4 dd(NTMAX*12000)
-  real*8 tsec,tseq
   character(len=20) :: datetime
-  character(len=12) :: mycall, hiscall, ctime
+  character(len=12) :: mycall, hiscall
   character(len=6) :: mygrid, hisgrid
   data ndec8/0/
   save
diff --git a/lib/ft8_decode.f90 b/lib/ft8_decode.f90
index c31279c70..6dca93e70 100644
--- a/lib/ft8_decode.f90
+++ b/lib/ft8_decode.f90
@@ -64,7 +64,6 @@ contains
     integer itone_save(NN,MAX_EARLY)
     real f1_save(MAX_EARLY)
     real xdt_save(MAX_EARLY)
-    integer(c_int) :: ihsym
 
     save s,dd,dd1,ndec_early,itone_save,f1_save,xdt_save,lsubtracted
 
diff --git a/lib/jt9.f90 b/lib/jt9.f90
index bee033822..7656f51e2 100644
--- a/lib/jt9.f90
+++ b/lib/jt9.f90
@@ -308,23 +308,23 @@ program jt9
         shared_data%params%nzhsym=nearly
         id2a(1:nearly*3456)=shared_data%id2(1:nearly*3456)
         id2a(nearly*3456+1:)=0
-        call multimode_decoder(shared_data%ipc(1),shared_data%ss,id2a,      &
+        call multimode_decoder(shared_data%ss,id2a,      &
              shared_data%params,nfsample)
         nearly=47
         shared_data%params%nzhsym=nearly
         id2a(1:nearly*3456)=shared_data%id2(1:nearly*3456)
         id2a(nearly*3456+1:)=0
-        call multimode_decoder(shared_data%ipc(1),shared_data%ss,id2a,      &
+        call multimode_decoder(shared_data%ss,id2a,      &
              shared_data%params,nfsample)
         id2a(nearly*3456+1:50*3456)=shared_data%id2(nearly*3456+1:50*3456)
         id2a(50*3456+1:)=0
         shared_data%params%nzhsym=50
-        call multimode_decoder(shared_data%ipc(1),shared_data%ss,id2a,      &
+        call multimode_decoder(shared_data%ss,id2a,      &
              shared_data%params,nfsample)
         cycle
      endif
 ! Normal decoding pass
-     call multimode_decoder(shared_data%ipc(1),shared_data%ss,shared_data%id2, &
+     call multimode_decoder(shared_data%ss,shared_data%id2, &
           shared_data%params,nfsample)
   enddo
 
diff --git a/lib/jt9a.f90 b/lib/jt9a.f90
index 4ad233855..b0df912ca 100644
--- a/lib/jt9a.f90
+++ b/lib/jt9a.f90
@@ -61,19 +61,16 @@ subroutine jt9a()
      local_params%nzhsym=nearly
      id2a(1:nearly*3456)=shared_data%id2(1:nearly*3456)
      id2a(nearly*3456+1:)=0
-     call multimode_decoder(shared_data%ipc(1),shared_data%ss,id2a,    &
-          local_params,12000)
+     call multimode_decoder(shared_data%ss,id2a,local_params,12000)
      nearly=47
      local_params%nzhsym=nearly
      id2a(1:nearly*3456)=shared_data%id2(1:nearly*3456)
      id2a(nearly*3456+1:)=0
-     call multimode_decoder(shared_data%ipc(1),shared_data%ss,id2a,    &
-          local_params,12000)
+     call multimode_decoder(shared_data%ss,id2a,local_params,12000)
      local_params%nzhsym=50
   endif
 ! Normal decoding pass
-  call multimode_decoder(shared_data%ipc(1),shared_data%ss,shared_data%id2,  &
-       local_params,12000)
+  call multimode_decoder(shared_data%ss,shared_data%id2,local_params,12000)
   call timer('decoder ',1)