diff --git a/library/bignum_core.c b/library/bignum_core.c
index a416a01..b0ffa37 100644
--- a/library/bignum_core.c
+++ b/library/bignum_core.c
@@ -33,6 +33,39 @@
 #include "bn_mul.h"
 #include "constant_time_internal.h"
 
+size_t mbedtls_mpi_core_clz(mbedtls_mpi_uint a)
+{
+#if defined(__has_builtin)
+#if __has_builtin(__builtin_clz)
+    if (sizeof(mbedtls_mpi_uint) == sizeof(unsigned int)) {
+        return (size_t) __builtin_clz(a);
+    }
+#endif
+#if __has_builtin(__builtin_clzl)
+    if (sizeof(mbedtls_mpi_uint) == sizeof(unsigned long)) {
+        return (size_t) __builtin_clzl(a);
+    }
+#endif
+#if __has_builtin(__builtin_clzll)
+    if (sizeof(mbedtls_mpi_uint) == sizeof(unsigned long long)) {
+        return (size_t) __builtin_clzll(a);
+    }
+#endif
+#endif
+    size_t j;
+    mbedtls_mpi_uint mask = (mbedtls_mpi_uint) 1 << (biL - 1);
+
+    for (j = 0; j < biL; j++) {
+        if (a & mask) {
+            break;
+        }
+
+        mask >>= 1;
+    }
+
+    return j;
+}
+
 size_t mbedtls_mpi_core_bitlen(const mbedtls_mpi_uint *A, size_t A_limbs)
 {
     int i;
diff --git a/library/bignum_core.h b/library/bignum_core.h
index d8731b3..158d2b3 100644
--- a/library/bignum_core.h
+++ b/library/bignum_core.h
@@ -109,38 +109,7 @@
  * \return      The number of leading zero bits in \p a, if \p a != 0.
  *              If \p a == 0, the result is undefined.
  */
-static inline size_t mbedtls_mpi_core_clz(mbedtls_mpi_uint a)
-{
-#if defined(__has_builtin)
-#if __has_builtin(__builtin_clz)
-    if (sizeof(mbedtls_mpi_uint) == sizeof(unsigned int)) {
-        return (size_t) __builtin_clz(a);
-    }
-#endif
-#if __has_builtin(__builtin_clzl)
-    if (sizeof(mbedtls_mpi_uint) == sizeof(unsigned long)) {
-        return (size_t) __builtin_clzl(a);
-    }
-#endif
-#if __has_builtin(__builtin_clzll)
-    if (sizeof(mbedtls_mpi_uint) == sizeof(unsigned long long)) {
-        return (size_t) __builtin_clzll(a);
-    }
-#endif
-#endif
-    size_t j;
-    mbedtls_mpi_uint mask = (mbedtls_mpi_uint) 1 << (biL - 1);
-
-    for (j = 0; j < biL; j++) {
-        if (a & mask) {
-            break;
-        }
-
-        mask >>= 1;
-    }
-
-    return j;
-}
+size_t mbedtls_mpi_core_clz(mbedtls_mpi_uint a);
 
 /** Return the minimum number of bits required to represent the value held
  * in the MPI.