diff --git a/configure.ac b/configure.ac
index 75e3c85b..10157291 100644
--- a/configure.ac
+++ b/configure.ac
@@ -13,6 +13,7 @@ gl_EARLY
 
 AM_PROG_AR
 AM_PROG_CC_C_O
+AC_PROG_SED
 if [ test "$GCC" = "yes" ];then
 	CFLAGS="$CFLAGS -Wall"
 fi
diff --git a/doc/Makefile.am b/doc/Makefile.am
index 00e92bc5..4bc9b29f 100644
--- a/doc/Makefile.am
+++ b/doc/Makefile.am
@@ -6,17 +6,17 @@ EXTRA_DIST = design.dia sample.config scripts/ocserv-script sample.passwd \
 dist_man_MANS = ocserv.8 ocpasswd.8 occtl.8
 
 ocserv.8: ../src/ocserv-args.def
-	-sed 's/@subheading \(.*\)/@*\n@var{\1}\n@*/' $< > "$<".tmp && \
+	-$(SED) 's/@subheading \(.*\)/@*\n@var{\1}\n@*/' $< > "$<".tmp && \
 	@AUTOGEN@ -L../src -DMAN_SECTION=8 -Tagman-cmd.tpl "$<".tmp && \
 	rm -f "$<".tmp
 
 occtl.8: ../src/occtl-args.def
-	-sed 's/@subheading \(.*\)/@*\n@var{\1}\n@*/' $< > "$<".tmp && \
+	-$(SED) 's/@subheading \(.*\)/@*\n@var{\1}\n@*/' $< > "$<".tmp && \
 	@AUTOGEN@ -L../src -DMAN_SECTION=8 -Tagman-cmd.tpl "$<".tmp && \
 	rm -f "$<".tmp
 
 ocpasswd.8: ../src/ocpasswd-args.def
-	-sed 's/@subheading \(.*\)/@*\n@var{\1}\n@*/' $< > "$<".tmp && \
+	-$(SED) 's/@subheading \(.*\)/@*\n@var{\1}\n@*/' $< > "$<".tmp && \
 	@AUTOGEN@ -L../src -DMAN_SECTION=8 -Tagman-cmd.tpl "$<".tmp && \
 	rm -f "$<".tmp