diff --git a/rust-unicode-normalization.spec b/rust-unicode-normalization.spec
index 876e82d..d2aee47 100644
--- a/rust-unicode-normalization.spec
+++ b/rust-unicode-normalization.spec
@@ -21,6 +21,7 @@ Patch0:         unicode-normalization-fix-metadata.diff
 ExclusiveArch:  %{rust_arches}
 
 BuildRequires:  rust-packaging
+BuildRequires:  (crate(smallvec/default) >= 0.6.0 with crate(smallvec/default) < 0.7.0)
 
 %global _description \
 This crate provides functions for normalization of Unicode strings,\