diff --git a/crypto/fipsmodule/bn/internal.h b/crypto/fipsmodule/bn/internal.h
index 623e0c6..3d368db 100644
--- a/crypto/fipsmodule/bn/internal.h
+++ b/crypto/fipsmodule/bn/internal.h
@@ -297,7 +297,7 @@
 void bn_mul_comba8(BN_ULONG r[16], const BN_ULONG a[8], const BN_ULONG b[8]);
 
 // bn_sqr_comba8 sets |r| to |a|^2.
-void bn_sqr_comba8(BN_ULONG r[16], const BN_ULONG a[4]);
+void bn_sqr_comba8(BN_ULONG r[16], const BN_ULONG a[8]);
 
 // bn_sqr_comba4 sets |r| to |a|^2.
 void bn_sqr_comba4(BN_ULONG r[8], const BN_ULONG a[4]);