diff --git a/basis/math/primes/primes.factor b/basis/math/primes/primes.factor
index 8ed1675ca7..543be5bbdb 100644
--- a/basis/math/primes/primes.factor
+++ b/basis/math/primes/primes.factor
@@ -76,7 +76,7 @@ PRIVATE>
 : nprimes ( n -- seq )
     2 swap [ [ next-prime ] keep ] replicate nip ;
 
-: coprime? ( a b -- ? ) fast-gcd 1 = ; foldable
+: coprime? ( a b -- ? ) simple-gcd 1 = ; foldable
 
 : random-prime ( numbits -- p )
     [ ] [ 2^ ] [ random-bits* next-prime ] tri
diff --git a/extra/math/primes/solovay-strassen/solovay-strassen.factor b/extra/math/primes/solovay-strassen/solovay-strassen.factor
index 12a940f2f0..3daad08e6f 100644
--- a/extra/math/primes/solovay-strassen/solovay-strassen.factor
+++ b/extra/math/primes/solovay-strassen/solovay-strassen.factor
@@ -12,7 +12,7 @@ IN: math.primes.solovay-strassen
     numtrials iota [
         drop
         n 1 - [1,b) random :> a
-        a n fast-gcd 1 > [ t ] [
+        a n simple-gcd 1 > [ t ] [
             a n jacobi n mod'
             a n 1 - 2 /i n ^mod = not
         ] if