--- a/plugins/wildmidi/src/wildmidi_lib.c
+++ b/plugins/wildmidi/src/wildmidi_lib.c
@@ -394,11 +394,11 @@ free_gauss (void) {
     }
 }
 
-unsigned long int delay_size[4][2];
-signed long int a[5][2];
-signed long int b[5][2];
-signed long int gain_in[4];
-signed long int gain_out[4];
+static unsigned long int delay_size[4][2];
+static signed long int a[5][2];
+static signed long int b[5][2];
+static signed long int gain_in[4];
+static signed long int gain_out[4];
 
 void init_lowpass (void) {
        float c = 0;