diff --git a/src/lib/Makefile.am b/src/lib/Makefile.am
index 7d2047f516..b9ea209c0c 100644
--- a/src/lib/Makefile.am
+++ b/src/lib/Makefile.am
@@ -269,6 +269,7 @@ headers = \
 	safe-mkstemp.h \
 	sendfile-util.h \
 	seq-range-array.h \
+	sha-common.h \
 	sha1.h \
 	sha2.h \
 	sort.h \
diff --git a/src/lib/sha-common.h b/src/lib/sha-common.h
new file mode 100644
index 0000000000..47c58feac1
--- /dev/null
+++ b/src/lib/sha-common.h
@@ -0,0 +1,9 @@
+#ifndef SHA_COMMON
+
+#define SHA256_RESULTLEN (256 / 8)
+#define SHA256_BLOCK_SIZE (512 / 8)
+
+#define SHA512_RESULTLEN (512 / 8)
+#define SHA512_BLOCK_SIZE (1024 / 8)
+
+#endif
diff --git a/src/lib/sha2.h b/src/lib/sha2.h
index b04f93ae5a..5d9d2f0b04 100644
--- a/src/lib/sha2.h
+++ b/src/lib/sha2.h
@@ -35,12 +35,7 @@
 #define SHA2_H
 
 #include "hash-method.h"
-
-#define SHA256_RESULTLEN (256 / 8)
-#define SHA256_BLOCK_SIZE (512 / 8)
-
-#define SHA512_RESULTLEN (512 / 8)
-#define SHA512_BLOCK_SIZE (1024 / 8)
+#include "sha-common.h"
 
 struct sha256_ctx {
 	size_t tot_len;