Index: gmic-1.6.0.3/src/Makefile
===================================================================
--- gmic-1.6.0.3.orig/src/Makefile
+++ gmic-1.6.0.3/src/Makefile
@@ -134,11 +134,13 @@ endif
 ifneq ($(OS),Darwin)
 CHECKIMAGE_CFLAGS = -Dgmic_check_image
 endif
 
+ifndef NO_OPENMP
 # Flags to enable parallelization using OpenMP.
 OPENMP_CFLAGS = -fopenmp -Dcimg_use_openmp
 OPENMP_LIBS = -lgomp
+endif
 
 # Flags to enable image display, using X11
 # (keep /usr/ dirname here since X11 is located in /usr/ on Mac too).
 # This requires the presence of the X11 include and library files.