diff --git a/lib/src/phy/rf/rf_lime_imp.c b/lib/src/phy/rf/rf_lime_imp.c
index 73eaa2e8cf..fa614313c9 100644
--- a/lib/src/phy/rf/rf_lime_imp.c
+++ b/lib/src/phy/rf/rf_lime_imp.c
@@ -73,7 +73,7 @@ typedef struct {
   pthread_t async_thread;
 } rf_lime_handler_t;
 
-cf_t zero_mem[64 * 1024];
+static cf_t zero_mem[64 * 1024];
 
 #if HAVE_ASYNC_THREAD
 static void log_overflow(rf_lime_handler_t* h)
diff --git a/lib/src/phy/rf/rf_soapy_imp.c b/lib/src/phy/rf/rf_soapy_imp.c
index 642e07a29f..5ad25a1b67 100644
--- a/lib/src/phy/rf/rf_soapy_imp.c
+++ b/lib/src/phy/rf/rf_soapy_imp.c
@@ -76,7 +76,7 @@ typedef struct {
   uint32_t num_stream_curruption;
 } rf_soapy_handler_t;
 
-cf_t zero_mem[64 * 1024];
+static cf_t zero_mem[64 * 1024];
 
 static void log_overflow(rf_soapy_handler_t* h)
 {