diff --git a/library/ecp.c b/library/ecp.c
index 83df037624..1ba2143a7e 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -2048,9 +2048,13 @@ static int ecp_mul_comb_core( const mbedtls_ecp_group *grp, mbedtls_ecp_point *R
         i = d;
         MBEDTLS_MPI_CHK( ecp_select_comb( grp, R, T, T_size, x[i] ) );
         MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &R->Z, 1 ) );
+
+        int have_rng = 1;
 #if defined(MBEDTLS_ECP_NO_INTERNAL_RNG)
-        if( f_rng != 0 )
+        if( f_rng == 0 )
+            have_rng = 0;
 #endif
+        if( have_rng )
             MBEDTLS_MPI_CHK( ecp_randomize_jac( grp, R, f_rng, p_rng ) );
     }
 
@@ -2184,9 +2188,12 @@ final_norm:
      *
      * Avoid the leak by randomizing coordinates before we normalize them.
      */
+    int have_rng = 1;
 #if defined(MBEDTLS_ECP_NO_INTERNAL_RNG)
-    if( f_rng != 0 )
+    if( f_rng == 0 )
+        have_rng = 0;
 #endif
+    if( have_rng )
         MBEDTLS_MPI_CHK( ecp_randomize_jac( grp, RR, f_rng, p_rng ) );
 
     MBEDTLS_MPI_CHK( ecp_normalize_jac( grp, RR ) );
@@ -2590,9 +2597,12 @@ static int ecp_mul_mxz( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
     MOD_ADD( RP.X );
 
     /* Randomize coordinates of the starting point */
+    int have_rng = 1;
 #if defined(MBEDTLS_ECP_NO_INTERNAL_RNG)
-    if( f_rng != NULL )
+    if( f_rng == NULL )
+        have_rng = 0;
 #endif
+    if( have_rng )
         MBEDTLS_MPI_CHK( ecp_randomize_mxz( grp, &RP, f_rng, p_rng ) );
 
     /* Loop invariant: R = result so far, RP = R + P */
@@ -2625,9 +2635,12 @@ static int ecp_mul_mxz( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
      *
      * Avoid the leak by randomizing coordinates before we normalize them.
      */
+    have_rng = 1;
 #if defined(MBEDTLS_ECP_NO_INTERNAL_RNG)
-    if( f_rng != NULL )
+    if( f_rng == NULL )
+        have_rng = 0;
 #endif
+    if( have_rng )
         MBEDTLS_MPI_CHK( ecp_randomize_mxz( grp, R, f_rng, p_rng ) );
 
     MBEDTLS_MPI_CHK( ecp_normalize_mxz( grp, R ) );