diff --git a/build.rs b/build.rs
index 3a2c092..13c3ab9 100644
--- a/build.rs
+++ b/build.rs
@@ -29,6 +29,22 @@ impl PkgConfigTemplate {
             ("DESCRIPTION".to_string(), env!("CARGO_PKG_DESCRIPTION").to_string()),
             ("VERSION".to_string(), env!("CARGO_PKG_VERSION").to_string()),
             ("HOMEPAGE".to_string(), env!("CARGO_PKG_HOMEPAGE").to_string()),
+            ("REQUIRES".to_string(),
+             if cfg!(feature = "crypto-botan") {
+                 "botan-2"
+             } else if cfg!(feature = "crypto-nettle") {
+                 "nettle"
+             } else if cfg!(feature = "crypto-openssl") {
+                 "libssl"
+             } else if cfg!(feature = "crypto-cng") {
+                 ""
+             } else if cfg!(feature = "crypto-rust") {
+                 ""
+             } else {
+                 panic!("No cryptographic backend selected.  Try: \
+                         \"cargo build --no-default-features \
+                         --features crypto-openssl\"")
+             }.to_string()),
         ]);
 
         Ok(PkgConfigTemplate {
diff --git a/rpm-sequoia.pc.in b/rpm-sequoia.pc.in
index 64f7b93..28fe3dd 100644
--- a/rpm-sequoia.pc.in
+++ b/rpm-sequoia.pc.in
@@ -5,6 +5,6 @@ Name: @NAME@
 Description: @DESCRIPTION@
 URL: @HOMEPAGE@
 Version: @VERSION@
-Requires.private: nettle
+Requires.private: @REQUIRES@
 Cflags:
 Libs: -L${libdir} -lrpm_sequoia