diff --git a/lib/one_gadget/fetchers/amd64.rb b/lib/one_gadget/fetchers/amd64.rb
index eaa7998..c12f55b 100644
--- a/lib/one_gadget/fetchers/amd64.rb
+++ b/lib/one_gadget/fetchers/amd64.rb
@@ -33,7 +33,7 @@ def candidates
       #   ...
       #   call execve
       def jmp_case_candidates
-        `#{@objdump.command}|egrep '# #{bin_sh_hex}' -A 8`.split('--').map do |cand|
+        `#{@objdump.command}|grep -E '# #{bin_sh_hex}' -A 8`.split('--').map do |cand|
           cand = cand.lines.map(&:strip).reject(&:empty?)
           jmp_at = cand.index { |c| c.include?('jmp') }
           next nil if jmp_at.nil?
@@ -42,7 +42,7 @@ def jmp_case_candidates
           next if cand.any? { |c| c.include?(call_str) }
 
           jmp_addr = cand.last.scan(/jmp\s+([\da-f]+)\s/)[0][0].to_i(16)
-          dump = `#{@objdump.command(start: jmp_addr, stop: jmp_addr + 100)}|egrep '[0-9a-f]+:'`
+          dump = `#{@objdump.command(start: jmp_addr, stop: jmp_addr + 100)}|grep -E '[0-9a-f]+:'`
           remain = dump.lines.map(&:strip).reject(&:empty?)
           call_execve = remain.index { |r| r.match(/call.*<execve[^+]*>/) }
           next if call_execve.nil?
diff --git a/lib/one_gadget/fetchers/base.rb b/lib/one_gadget/fetchers/base.rb
index 11ea867..1a33c90 100644
--- a/lib/one_gadget/fetchers/base.rb
+++ b/lib/one_gadget/fetchers/base.rb
@@ -51,7 +51,7 @@ def find
       def candidates(&block)
         call_regexp = "#{call_str}.*<(exec[^+]*|posix_spawn[^+]*)>$"
         cands = []
-        `#{@objdump.command}|egrep '#{call_regexp}' -B 30`.split('--').each do |cand|
+        `#{@objdump.command}|grep -E '#{call_regexp}' -B 30`.split('--').each do |cand|
           lines = cand.lines.map(&:strip).reject(&:empty?)
           # split with call_regexp
           loop do