diff --git a/src/farchive.cpp b/src/farchive.cpp
index a589df50a..ac6c88631 100644
--- a/src/farchive.cpp
+++ b/src/farchive.cpp
@@ -402,14 +402,11 @@ void FCompressedFile::Explode ()
 			uLong newlen;
 
 			newlen = expandsize;
-			_heapchk();
 			r = uncompress (expand, &newlen, m_Buffer + 8, cprlen);
 			if (r != Z_OK || newlen != expandsize)
 			{
-				_heapchk();
 				M_Free (expand);
-				_heapchk();
-				I_Error ("Could not decompress buffer: %s", M_ZLibError(r));
+				I_Error ("Could not decompress buffer: %s", M_ZLibError(r).GetChars());
 			}
 		}
 		else
diff --git a/src/files.cpp b/src/files.cpp
index d205429e1..80f0f8303 100644
--- a/src/files.cpp
+++ b/src/files.cpp
@@ -224,7 +224,7 @@ FileReaderZ::FileReaderZ (FileReader &file, bool zip)
 
 	if (err != Z_OK)
 	{
-		I_Error ("FileReaderZ: inflateInit failed: %s\n", M_ZLibError(err));
+		I_Error ("FileReaderZ: inflateInit failed: %s\n", M_ZLibError(err).GetChars());
 	}
 }
 
diff --git a/src/g_game.cpp b/src/g_game.cpp
index 3aa4d3059..3d18f8fad 100644
--- a/src/g_game.cpp
+++ b/src/g_game.cpp
@@ -2513,7 +2513,7 @@ bool G_ProcessIFFDemo (char *mapname)
 		int r = uncompress (uncompressed, &uncompSize, demo_p, uLong(zdembodyend - demo_p));
 		if (r != Z_OK)
 		{
-			Printf ("Could not decompress demo! %s\n", M_ZLibError(r));
+			Printf ("Could not decompress demo! %s\n", M_ZLibError(r).GetChars());
 			delete[] uncompressed;
 			return true;
 		}
diff --git a/src/i_net.cpp b/src/i_net.cpp
index 5b0b35907..57543b29d 100644
--- a/src/i_net.cpp
+++ b/src/i_net.cpp
@@ -303,7 +303,7 @@ void PacketGet (void)
 //			Printf("recv %d/%lu\n", c, msgsize + 1);
 			if (err != Z_OK)
 			{
-				Printf("Net decompression failed (zlib error %s)\n", M_ZLibError(err));
+				Printf("Net decompression failed (zlib error %s)\n", M_ZLibError(err).GetChars());
 				// Pretend no packet
 				doomcom.remotenode = -1;
 				return;