diff --git a/corrvir/corrvir.c b/corrvir/corrvir.c
index 10bf2944ad7928fe99de994fb4d7556b7a390454..44a0025ce907aeec456c9d1794c58e6fa8689cc4 100644
--- a/corrvir/corrvir.c
+++ b/corrvir/corrvir.c
@@ -19,6 +19,7 @@ void read_sutrace_at_position(FILE *fp, int itrace, complex *tracedata, complex
 
 int optncr(int n);
 void cr1fft(complex *cdata, float *data, int n, int sign);
+void rc1fft(float *rdata, complex *cdata, int n, int sign);
 
 int getFileInfo(char *file_name, int *n1, int *n2, float *d1, float *d2, int verbose);