diff --git a/CMakeLists.txt b/CMakeLists.txt
index f997cea582f..b1104a2a475 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -590,14 +590,14 @@ set(CMAKE_C_STANDARD_REQUIRED ON)
 set(CMAKE_C_EXTENSIONS ON)
 
 if (UNIX)
-  set( CMAKE_C_FLAGS "-Werror -Wno-pointer-sign -Wall -Wmissing-prototypes -Wmissing-declarations ${CMAKE_C_FLAGS}")
-  set( CMAKE_C_FLAGS "-Wno-error=deprecated-declarations -Wno-error=parentheses ${CMAKE_C_FLAGS}")
-  set( CMAKE_CXX_FLAGS "-Werror -Wall -Wmissing-declarations -Wno-error=parentheses ${CMAKE_CXX_FLAGS}")
-  set( CMAKE_CXX_FLAGS "-Wno-error=deprecated-declarations ${REGISTER_CXXFLAG} ${CMAKE_CXX_FLAGS}")
+  set( CMAKE_C_FLAGS "-Werror -Wall -Wmissing-prototypes -Wmissing-declarations ${CMAKE_C_FLAGS}")
+  set( CMAKE_C_FLAGS "-Wno-error=deprecated-declarations ${CMAKE_C_FLAGS}")
+  set( CMAKE_CXX_FLAGS "-Werror -Wall -Wmissing-declarations ${CMAKE_CXX_FLAGS}")
+  set( CMAKE_CXX_FLAGS "-Wno-error=deprecated-declarations ${CMAKE_CXX_FLAGS}")
   set( CMAKE_C_FLAGS_RELEASE "-O3 -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 ${CMAKE_C_FLAGS}")
 endif()
 if (MINGW)
-  set( CMAKE_C_FLAGS "-Werror -Wno-pointer-sign -Wall -Wmissing-prototypes -Wmissing-declarations -Wno-error=deprecated-declarations ${CMAKE_C_FLAGS}")
+  set( CMAKE_C_FLAGS "-Werror -Wall -Wmissing-prototypes -Wmissing-declarations -Wno-error=deprecated-declarations ${CMAKE_C_FLAGS}")
   set( CMAKE_CXX_FLAGS "-DWINVER=0x0500 -D_EMULATE_GLIBC=0 ${CMAKE_CXX_FLAGS}") # Workaround for bug in gtest on mingw, see https://github.com/google/googletest/issues/893 and https://github.com/google/googletest/issues/920
 endif()
 
diff --git a/gnucash/import-export/aqb/gnc-gwen-gui.c b/gnucash/import-export/aqb/gnc-gwen-gui.c
index a39be8870b4..44a492e82c1 100644
--- a/gnucash/import-export/aqb/gnc-gwen-gui.c
+++ b/gnucash/import-export/aqb/gnc-gwen-gui.c
@@ -1575,8 +1575,8 @@ checkcert_cb(GWEN_GUI *gwen_gui, const GWEN_SSLCERTDESCR *cert,
     hash = GWEN_SslCertDescr_GetFingerPrint(cert);
     status = GWEN_SslCertDescr_GetStatusText(cert);
 
-    g_checksum_update (gcheck, hash, strlen (hash));
-    g_checksum_update (gcheck, status, strlen (status));
+    g_checksum_update (gcheck, (const guchar *)hash, strlen (hash));
+    g_checksum_update (gcheck, (const guchar *)status, strlen (status));
 
     /* Did we get the permanently accepted certs from AqBanking? */
     if (gui->permanently_accepted_certs)
@@ -1597,7 +1597,7 @@ checkcert_cb(GWEN_GUI *gwen_gui, const GWEN_SSLCERTDESCR *cert,
         g_warning("Can't check permanently accepted certs from invalid AqBanking cert store.");
     }
 
-    g_checksum_get_digest (gcheck, cert_hash, &hashlen);
+    g_checksum_get_digest (gcheck, (guint8 *)cert_hash, &hashlen);
     g_checksum_free (gcheck);
     g_assert (hashlen <= sizeof (cert_hash));