diff --git a/dlls/winecoreaudio.drv/audio.c b/dlls/winecoreaudio.drv/audio.c
index f48a5aa9183..8223dff7a39 100644
--- a/dlls/winecoreaudio.drv/audio.c
+++ b/dlls/winecoreaudio.drv/audio.c
@@ -264,7 +264,6 @@ OSStatus CoreAudio_wiAudioUnitIOProc(void *inRefCon,
 
 static const char * getMessage(UINT msg)
 {
-    static char unknown[32];
 #define MSG_TO_STR(x) case x: return #x
     switch(msg) {
         MSG_TO_STR(DRVM_INIT);
@@ -306,8 +305,7 @@ static const char * getMessage(UINT msg)
         MSG_TO_STR(DRV_QUERYDSOUNDDESC);
     }
 #undef MSG_TO_STR
-    sprintf(unknown, "UNKNOWN(0x%04x)", msg);
-    return unknown;
+    return wine_dbg_sprintf("UNKNOWN(0x%04x)", msg);
 }
 
 #define kStopLoopMessage 0
diff --git a/dlls/winecoreaudio.drv/mixer.c b/dlls/winecoreaudio.drv/mixer.c
index 7c01c57ddd5..389caad7d58 100644
--- a/dlls/winecoreaudio.drv/mixer.c
+++ b/dlls/winecoreaudio.drv/mixer.c
@@ -92,7 +92,6 @@ static int numMixers = 1;
 
 static const char * getMessage(UINT uMsg)
 {
-    static char str[64];
 #define MSG_TO_STR(x) case x: return #x;
     switch (uMsg) {
         MSG_TO_STR(DRVM_INIT);
@@ -109,13 +108,11 @@ static const char * getMessage(UINT uMsg)
         MSG_TO_STR(MXDM_SETCONTROLDETAILS);
     }
 #undef MSG_TO_STR
-        sprintf(str, "UNKNOWN(%08x)", uMsg);
-    return str;
+    return wine_dbg_sprintf("UNKNOWN(%08x)", uMsg);
 }
 
 static const char * getControlType(DWORD dwControlType)
 {
-    static char str[64];
 #define TYPE_TO_STR(x) case x: return #x;
     switch (dwControlType) {
         TYPE_TO_STR(MIXERCONTROL_CONTROLTYPE_CUSTOM);
@@ -151,13 +148,11 @@ static const char * getControlType(DWORD dwControlType)
         TYPE_TO_STR(MIXERCONTROL_CONTROLTYPE_MILLITIME);
     }
 #undef TYPE_TO_STR
-        sprintf(str, "UNKNOWN(%08x)", dwControlType);
-    return str;
+    return wine_dbg_sprintf("UNKNOWN(%08x)", dwControlType);
 }
 
 static const char * getComponentType(DWORD dwComponentType)
 {
-    static char str[64];
 #define TYPE_TO_STR(x) case x: return #x;
     switch (dwComponentType) {
         TYPE_TO_STR(MIXERLINE_COMPONENTTYPE_DST_UNDEFINED);
@@ -182,13 +177,11 @@ static const char * getComponentType(DWORD dwComponentType)
         TYPE_TO_STR(MIXERLINE_COMPONENTTYPE_SRC_ANALOG);
     }
 #undef TYPE_TO_STR
-        sprintf(str, "UNKNOWN(%08x)", dwComponentType);
-    return str;
+    return wine_dbg_sprintf("UNKNOWN(%08x)", dwComponentType);
 }
 
 static const char * getTargetType(DWORD dwType)
 {
-    static char str[64];
 #define TYPE_TO_STR(x) case x: return #x;
     switch (dwType) {
         TYPE_TO_STR(MIXERLINE_TARGETTYPE_UNDEFINED);
@@ -199,8 +192,7 @@ static const char * getTargetType(DWORD dwType)
         TYPE_TO_STR(MIXERLINE_TARGETTYPE_AUX);
     }
 #undef TYPE_TO_STR
-        sprintf(str, "UNKNOWN(%08x)", dwType);
-    return str;
+    return wine_dbg_sprintf("UNKNOWN(%08x)", dwType);
 }
 
 /* FIXME is there a better way ? */