diff --git a/scripts/prepare_instrumentation.sh b/scripts/prepare_instrumentation.sh
index 17179fc57c62800b71b6624616220586be7b2cf1..c748f19aca4745df84b90a3e7132235fdfa36555 100755
--- a/scripts/prepare_instrumentation.sh
+++ b/scripts/prepare_instrumentation.sh
@@ -106,8 +106,8 @@ find $targetdir -name "*.[ch]" -exec sed -i.bak -e "s/\(0x[0-9a-fA-F]*\)UL/\(\(u
 "tools/$system/wmc_tool" -m "$targetdir/apps/decoder.c" "$targetdir/lib_dec/*.c" "$targetdir/lib_rend/*.c" >> /dev/null
 
 # automatically enable #define WMOPS in options.h
-sed -i.bak -e "s/\/\*\s*\(#define\s*WMOPS\)\s*\*\//\1/g" $targetdir/lib_com/options.h
-sed -i.bak -e "s/\/\/\s*\(#define\s*WMOPS\)/\1/g"        $targetdir/lib_com/options.h
+sed -i.bak -e "s/\/\*[[:space:]]*\(#define[[:space:]]*WMOPS\)[[:space:]]*\*\//\1/g" $targetdir/lib_com/options.h
+sed -i.bak -e "s/\/\/[[:space:]]*\(#define[[:space:]]*WMOPS\)/\1/g"        $targetdir/lib_com/options.h
 
 # return to start dir
 cd "$currdir"