diff --git a/CMakeLists.txt b/CMakeLists.txt
index a330f6187..29984ba52 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -424,6 +424,7 @@ set (wsjt_FSRCS
   lib/ft8/ft8code.f90
   lib/ft8/ft8_downsample.f90
   lib/ft8/ft8q3.f90
+  lib/ft8/test_ft8q3.f90
   lib/ft8/ft8sim.f90
   lib/gen4.f90
   lib/gen65.f90
@@ -1178,8 +1179,8 @@ target_link_libraries (ft4code wsjt_fort wsjt_cxx)
 add_executable (ft8sim lib/ft8/ft8sim.f90)
 target_link_libraries (ft8sim wsjt_fort wsjt_cxx)
 
-add_executable (ft8q3 lib/ft8/ft8q3.f90)
-target_link_libraries (ft8q3 wsjt_fort wsjt_cxx)
+add_executable (test_ft8q3 lib/ft8/test_ft8q3.f90)
+target_link_libraries (test_ft8q3 wsjt_fort wsjt_cxx)
 
 add_executable (msk144sim lib/msk144sim.f90)
 target_link_libraries (msk144sim wsjt_fort wsjt_cxx)
diff --git a/lib/ft8/test_ft8q3.f90 b/lib/ft8/test_ft8q3.f90
new file mode 100644
index 000000000..06ad11ef0
--- /dev/null
+++ b/lib/ft8/test_ft8q3.f90
@@ -0,0 +1,84 @@
+program test_ft8q3
+
+! Test q3-style decodes for FT8.
+
+  use packjt77
+  parameter(NN=79,NSPS=32)
+  parameter(NWAVE=NN*NSPS)               !2528
+  parameter(NZ=3200,NLAGS=NZ-NWAVE)
+  character arg*12
+  character msg37*37
+  character c77*77
+  complex cwave(0:NWAVE-1)
+  complex cd(0:NZ-1)
+  complex z
+  real xjunk(NWAVE)
+  real ccf(0:NLAGS-1)
+  integer itone(NN)
+  integer*1 msgbits(77)
+
+! Get command-line argument(s)
+  nargs=iargc()
+  if(nargs.ne.3) then
+     print*,'Usage:    ft8q3 DT f0 "message"'
+     go to 999
+  endif
+  call getarg(1,arg)
+  read(arg,*) xdt                        !Time offset from nominal (s)
+  call getarg(2,arg)
+  read(arg,*) f0                         !Frequency (Hz)
+  call getarg(3,msg37)                   !Message to be transmitted
+
+  fs=200.0                               !Sample rate (Hz)
+  dt=1.0/fs                              !Sample interval (s)
+  bt=2.0                         
+
+! Source-encode, then get itone()
+  i3=-1
+  n3=-1
+  call pack77(msg37,i3,n3,c77)
+  call genft8(msg37,i3,n3,msgsent37,msgbits,itone)
+! Generate complex cwave
+  call gen_ft8wave(itone,NN,NSPS,bt,fs,f0,cwave,xjunk,1,NWAVE)
+
+  do i=0,NZ-1
+     read(40,3040) cd(i)
+3040 format(17x,2f10.3)
+  enddo
+
+  lagbest=-1
+  ccfbest=0.
+  nsum=32*2
+  do lag=0,nlags-1
+     z=0.
+     s=0.
+     do i=0,NWAVE-1
+        z=z + cd(i+lag)*conjg(cwave(i))
+        if(mod(i,nsum).eq.nsum-1 .or. i.eq.NWAVE-1) then
+           s=s + abs(z)
+           z=0.
+        endif
+     enddo
+!     ccf(lag)=abs(z)
+     ccf(lag)=s
+     write(42,3042) lag-100,(lag-100)/200.0,ccf(lag)
+3042 format(i5,f10.3,f10.0)
+     if(ccf(lag).gt.ccfbest) then
+        ccfbest=ccf(lag)
+        lagbest=lag
+     endif
+  enddo
+
+  z=0.
+  do i=0,NWAVE-1
+     z=z + cd(i+lagbest)*conjg(cwave(i))
+     if(mod(i,32).eq.31) then
+        amp=abs(z)**2
+        pha=atan2(aimag(z),real(z))
+        j=i/32
+        write(43,3043) z,j,amp,pha
+3043    format(2f12.0,i6,f12.0,f12.6)
+     endif
+  enddo
+
+999 end program test_ft8q3