diff --git a/libp2p/multibase.nim b/libp2p/multibase.nim
index f5f824d70..8d392f1b7 100644
--- a/libp2p/multibase.nim
+++ b/libp2p/multibase.nim
@@ -11,7 +11,7 @@
 ##
 ## TODO:
 ## 1. base32z
-## 
+##
 
 {.push raises: [Defect].}
 
@@ -24,17 +24,17 @@ type
 
   MultiBase* = object
 
-  MBCodeSize = proc(length: int): int {.nimcall, raises: [Defect].}
+  MBCodeSize = proc(length: int): int {.nimcall, gcsafe, noSideEffect, raises: [Defect].}
 
   MBCodec = object
     code: char
     name: string
     encr: proc(inbytes: openarray[byte],
                outbytes: var openarray[char],
-               outlen: var int): MultibaseStatus {.nimcall, raises: [Defect].}
+               outlen: var int): MultibaseStatus {.nimcall, gcsafe, noSideEffect, raises: [Defect].}
     decr: proc(inbytes: openarray[char],
                outbytes: var openarray[byte],
-               outlen: var int): MultibaseStatus {.nimcall, raises: [Defect].}
+               outlen: var int): MultibaseStatus {.nimcall, gcsafe, noSideEffect, raises: [Defect].}
     encl: MBCodeSize
     decl: MBCodeSize
 
diff --git a/libp2p/multihash.nim b/libp2p/multihash.nim
index bc0f9285d..4d7d066d9 100644
--- a/libp2p/multihash.nim
+++ b/libp2p/multihash.nim
@@ -42,7 +42,7 @@ const
 
 type
   MHashCoderProc* = proc(data: openarray[byte],
-                         output: var openarray[byte]) {.nimcall, gcsafe, raises: [Defect].}
+                         output: var openarray[byte]) {.nimcall, gcsafe, noSideEffect, raises: [Defect].}
   MHash* = object
     mcodec*: MultiCodec
     size*: int
diff --git a/libp2p/transcoder.nim b/libp2p/transcoder.nim
index 3d9714092..c9f35cc5c 100644
--- a/libp2p/transcoder.nim
+++ b/libp2p/transcoder.nim
@@ -13,7 +13,7 @@ import vbuffer
 type
   Transcoder* = object
     stringToBuffer*: proc(s: string,
-                          vb: var VBuffer): bool {.nimcall, gcsafe, raises: [Defect].}
+                          vb: var VBuffer): bool {.nimcall, gcsafe, noSideEffect, raises: [Defect].}
     bufferToString*: proc(vb: var VBuffer,
-                          s: var string): bool {.nimcall, gcsafe, raises: [Defect].}
-    validateBuffer*: proc(vb: var VBuffer): bool {.nimcall, gcsafe, raises: [Defect].}
+                          s: var string): bool {.nimcall, gcsafe, noSideEffect, raises: [Defect].}
+    validateBuffer*: proc(vb: var VBuffer): bool {.nimcall, gcsafe, noSideEffect, raises: [Defect].}