ctffind 4.1.5 returns exit code -1

I am using ctffind 4.1.5 binary. In both interactive and scripted modes the program finishes correctly (all output is generated properly), however the exit code is 0377 (-1 in decimal).

(gdb) run < foo
Starting program: /home/software/em/ctffind_V4.1.5/ctffind < foo
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".

** Welcome to Ctffind **

Version : 4.1.5
Compiled : Sep 9 2016
Mode : Scripted

Input image file name : BPV_1386b.mrc
Output diagnostic image file name : ctfEstimation.mrc
Pixel size : 2.474000
Acceleration voltage : 300.000000
Spherical aberration : 2.000000
Amplitude contrast : 0.100000
Size of amplitude spectrum to compute : 256
Minimum resolution : 49.480000
Maximum resolution : 7.068571
Minimum defocus : 2500.000000
Maximum defocus : 40000.000000
Defocus search step : 500.000000
Do you know what astigmatism is present? : no
Slower, more exhaustive search? : no
Use a restraint on astigmatism? : yes
Expected (tolerated) astigmatism : 100.000000
Find additional phase shift? : no
Do you want to set expert options? : yes
Resample micrograph if pixel size too small? : yes

Summary information for file BPV_1386b.mrc
Number of columns, rows, sections: 4608, 4720, 1
MRC data mode: 2
Bit depth: 32
Pixel size: 1.000 1.000 1.000
Bytes in symmetry header: 0
Label 1 :
Label 2 :
Label 3 :
Label 4 :
Label 5 :
Label 6 :
Label 7 :
Label 8 :
Label 9 :
Label 10 :

Working on micrograph 1 of 1
Estimated defocus values : 23931.39 , 23634.48 Angstroms
Estimated azimuth of astigmatism: 53.03 degrees
Score : 0.19586
Pixel size for fitting : 2.474 Angstroms
Thon rings with good fit up to : 6.0 Angstroms
CTF aliasing apparent from : 5.3 Angstroms

Summary of results : ctfEstimation.txt
Diagnostic images : ctfEstimation.mrc
Detailed results, including 1D fit profiles : ctfEstimation_avrot.txt
Use this command to plot 1D fit profiles : ctffind_plot_results.sh ctfEstimation_avrot.txt

[Inferior 1 (process 27648) exited with code 0377]

I realize this is a minor issue, however I use a wrapper around ctffind4 and would like to check the exit code to be sure the program finishes cleanly.