diff --git a/openair1/PHY/MODULATION/modulation_common.h b/openair1/PHY/MODULATION/modulation_common.h
index a131cdae63..df521b10da 100644
--- a/openair1/PHY/MODULATION/modulation_common.h
+++ b/openair1/PHY/MODULATION/modulation_common.h
@@ -38,7 +38,7 @@
    @param nb_prefix_samples The number of prefix/suffix/zero samples
    @param etype Type of extension (CYCLIC_PREFIX,CYCLIC_SUFFIX,ZEROS)
 */
-void PHY_ofdm_mod(int *input,
+void PHY_ofdm_mod(const int *input,
                   int *output,
                   int fftsize,
                   unsigned char nb_symbols,
diff --git a/openair1/PHY/MODULATION/ofdm_mod.c b/openair1/PHY/MODULATION/ofdm_mod.c
index 61487eb433..31c056b712 100644
--- a/openair1/PHY/MODULATION/ofdm_mod.c
+++ b/openair1/PHY/MODULATION/ofdm_mod.c
@@ -122,7 +122,7 @@ void nr_normal_prefix_mod(c16_t *txdataF, c16_t *txdata, uint8_t nsymb, const NR
 
 }
 
-void PHY_ofdm_mod(int *input, /// pointer to complex input
+void PHY_ofdm_mod(const int *input, /// pointer to complex input
                   int *output, /// pointer to complex output
                   int fftsize, /// FFT_SIZE
                   unsigned char nb_symbols, /// number of OFDM symbols