diff --git a/configure.ac b/configure.ac
index 23dbc54..23c17f4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -55,9 +55,12 @@ AC_DEFINE_UNQUOTED(HAVE_LITTLE_ENDIAN, $little_endian, [Little-endian system])
 AC_DEFINE_UNQUOTED(HAVE_BIG_ENDIAN, $big_endian, [Big-endian system])
 
 PKG_PROG_PKG_CONFIG()
-PKG_CHECK_MODULES(libcrypto, libcrypto,
-    [],
-    AC_MSG_ERROR([libcrypto (from the OpenSSL package) is required]))
+PKG_CHECK_MODULES(libcrypto, [libcrypto >= 3.0.0],
+                  [ac_have_openssl3=1],
+                  [PKG_CHECK_MODULES(libcrypto, libcrypto,
+                   [],
+                   AC_MSG_ERROR([libcrypto (from the OpenSSL package) is required]))])
+AM_CONDITIONAL(HAVE_OPENSSL3, test "$ac_have_openssl3" = "1")
 
 PKG_CHECK_MODULES(uuid, uuid,
     [],
diff --git a/src/Makefile.am b/src/Makefile.am
index e3f039b..38f93ff 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -4,6 +4,10 @@ bin_PROGRAMS = sbsign sbverify sbattach sbvarsign sbsiglist sbkeysync
 coff_headers = coff/external.h coff/pe.h
 AM_CFLAGS = -Wall -Wextra --std=gnu99
 
+if HAVE_OPENSSL3
+AM_CFLAGS += -DOPENSSL_API_COMPAT=0x10100000L
+endif
+
 common_SOURCES = idc.c idc.h image.c image.h fileio.c fileio.h \
 	efivars.h $(coff_headers)
 common_LDADD = ../lib/ccan/libccan.a $(libcrypto_LIBS)