diff --git a/server/cursor-channel.cpp b/server/cursor-channel.cpp
index f78dbba2..691c304d 100644
--- a/server/cursor-channel.cpp
+++ b/server/cursor-channel.cpp
@@ -26,7 +26,7 @@
 #include "reds.h"
 
 struct RedCursorPipeItem: public RedPipeItemNum<RED_PIPE_ITEM_TYPE_CURSOR> {
-    RedCursorPipeItem(RedCursorCmd *cmd);
+    explicit RedCursorPipeItem(RedCursorCmd *cmd);
     ~RedCursorPipeItem();
     RedCursorCmd *red_cursor;
 };
diff --git a/server/dispatcher.cpp b/server/dispatcher.cpp
index 0ddb63ae..1163681c 100644
--- a/server/dispatcher.cpp
+++ b/server/dispatcher.cpp
@@ -45,7 +45,7 @@ struct DispatcherMessage {
 
 struct DispatcherPrivate {
     SPICE_CXX_GLIB_ALLOCATOR
-    DispatcherPrivate(uint32_t init_max_message_type):
+    explicit DispatcherPrivate(uint32_t init_max_message_type):
         max_message_type(init_max_message_type)
     {
     }
diff --git a/server/inputs-channel.cpp b/server/inputs-channel.cpp
index 939d652c..9a1880cb 100644
--- a/server/inputs-channel.cpp
+++ b/server/inputs-channel.cpp
@@ -87,12 +87,12 @@ RedsState* spice_tablet_state_get_server(SpiceTabletState *st)
 }
 
 struct RedKeyModifiersPipeItem: public RedPipeItemNum<RED_PIPE_ITEM_KEY_MODIFIERS> {
-    RedKeyModifiersPipeItem(uint8_t modifiers);
+    explicit RedKeyModifiersPipeItem(uint8_t modifiers);
     uint8_t modifiers;
 };
 
 struct RedInputsInitPipeItem: public RedPipeItemNum<RED_PIPE_ITEM_INPUTS_INIT> {
-    RedInputsInitPipeItem(uint8_t modifiers);
+    explicit RedInputsInitPipeItem(uint8_t modifiers);
     uint8_t modifiers;
 };
 
diff --git a/server/reds.cpp b/server/reds.cpp
index 052bd6aa..3ae0216a 100644
--- a/server/reds.cpp
+++ b/server/reds.cpp
@@ -207,7 +207,7 @@ struct SPICE_ATTR_PACKED VDInternalBuf {
 
 struct RedCharDeviceVDIPort: public RedCharDevice
 {
-    RedCharDeviceVDIPort(RedsState *reds);
+    explicit RedCharDeviceVDIPort(RedsState *reds);
     RedCharDeviceVDIPort();
     ~RedCharDeviceVDIPort();
 
diff --git a/server/sound.cpp b/server/sound.cpp
index e5c8d3e8..322171a2 100644
--- a/server/sound.cpp
+++ b/server/sound.cpp
@@ -185,7 +185,7 @@ inline SndChannel* SndChannelClient::get_channel()
 
 struct PlaybackChannel final: public SndChannel
 {
-    PlaybackChannel(RedsState *reds);
+    explicit PlaybackChannel(RedsState *reds);
     void on_connect(RedClient *client, RedStream *stream,
                     int migration, RedChannelCapabilities *caps) override;
 };
@@ -193,7 +193,7 @@ struct PlaybackChannel final: public SndChannel
 
 struct RecordChannel final: public SndChannel
 {
-    RecordChannel(RedsState *reds);
+    explicit RecordChannel(RedsState *reds);
     void on_connect(RedClient *client, RedStream *stream,
                     int migration, RedChannelCapabilities *caps) override;
 };