diff --git a/src/lib/crypt_ops/crypto.c b/src/lib/crypt_ops/crypto.c
index d988473f49..e4f092c80c 100644
--- a/src/lib/crypt_ops/crypto.c
+++ b/src/lib/crypt_ops/crypto.c
@@ -129,26 +129,6 @@ crypto_cipher_free_(crypto_cipher_t *env)
   aes_cipher_free(env);
 }
 
-/** Copy <b>in</b> to the <b>outlen</b>-byte buffer <b>out</b>, adding spaces
- * every four characters. */
-void
-crypto_add_spaces_to_fp(char *out, size_t outlen, const char *in)
-{
-  int n = 0;
-  char *end = out+outlen;
-  tor_assert(outlen < SIZE_T_CEILING);
-
-  while (*in && out<end) {
-    *out++ = *in++;
-    if (++n == 4 && *in && out<end) {
-      n = 0;
-      *out++ = ' ';
-    }
-  }
-  tor_assert(out<end);
-  *out = '\0';
-}
-
 /* symmetric crypto */
 
 /** Encrypt <b>fromlen</b> bytes from <b>from</b> using the cipher
diff --git a/src/lib/crypt_ops/crypto.h b/src/lib/crypt_ops/crypto.h
index 6034c84174..993a65fb01 100644
--- a/src/lib/crypt_ops/crypto.h
+++ b/src/lib/crypt_ops/crypto.h
@@ -59,6 +59,4 @@ int crypto_cipher_decrypt_with_iv(const char *key,
                                   char *to, size_t tolen,
                                   const char *from, size_t fromlen);
 
-void crypto_add_spaces_to_fp(char *out, size_t outlen, const char *in);
-
 #endif /* !defined(TOR_CRYPTO_H) */
diff --git a/src/lib/crypt_ops/crypto_rsa.c b/src/lib/crypt_ops/crypto_rsa.c
index 5ec69d7319..f0fd6d5f4b 100644
--- a/src/lib/crypt_ops/crypto_rsa.c
+++ b/src/lib/crypt_ops/crypto_rsa.c
@@ -976,6 +976,26 @@ crypto_pk_get_hashed_fingerprint(crypto_pk_t *pk, char *fp_out)
   return 0;
 }
 
+/** Copy <b>in</b> to the <b>outlen</b>-byte buffer <b>out</b>, adding spaces
+ * every four characters. */
+void
+crypto_add_spaces_to_fp(char *out, size_t outlen, const char *in)
+{
+  int n = 0;
+  char *end = out+outlen;
+  tor_assert(outlen < SIZE_T_CEILING);
+
+  while (*in && out<end) {
+    *out++ = *in++;
+    if (++n == 4 && *in && out<end) {
+      n = 0;
+      *out++ = ' ';
+    }
+  }
+  tor_assert(out<end);
+  *out = '\0';
+}
+
 /** Check a siglen-byte long signature at <b>sig</b> against
  * <b>datalen</b> bytes of data at <b>data</b>, using the public key
  * in <b>env</b>. Return 0 if <b>sig</b> is a correct signature for
diff --git a/src/lib/crypt_ops/crypto_rsa.h b/src/lib/crypt_ops/crypto_rsa.h
index 51fc974821..c70e01c3f4 100644
--- a/src/lib/crypt_ops/crypto_rsa.h
+++ b/src/lib/crypt_ops/crypto_rsa.h
@@ -88,6 +88,7 @@ int crypto_pk_asn1_encode(const crypto_pk_t *pk, char *dest, size_t dest_len);
 crypto_pk_t *crypto_pk_asn1_decode(const char *str, size_t len);
 int crypto_pk_get_fingerprint(crypto_pk_t *pk, char *fp_out,int add_space);
 int crypto_pk_get_hashed_fingerprint(crypto_pk_t *pk, char *fp_out);
+void crypto_add_spaces_to_fp(char *out, size_t outlen, const char *in);
 
 MOCK_DECL(int, crypto_pk_public_checksig_digest,(crypto_pk_t *env,
           const char *data, size_t datalen, const char *sig, size_t siglen));