diff --git a/.appveyor-vcpkg.yml b/.appveyor-vcpkg.yml
index 6576b7a3..b579ac20 100644
--- a/.appveyor-vcpkg.yml
+++ b/.appveyor-vcpkg.yml
@@ -38,7 +38,7 @@ install:
 build_script:
   - mkdir build
   - cd build
-  - cmake -G "%generator%" -T "%toolset%" -Denable-pkgconfig=0 -DCMAKE_TOOLCHAIN_FILE=c:/Tools/vcpkg/scripts/buildsystems/vcpkg.cmake ..
+  - cmake -G "%generator%" -T "%toolset%" -Denable-pkgconfig=0 -DCMAKE_TOOLCHAIN_FILE=c:/Tools/vcpkg/scripts/buildsystems/vcpkg.cmake -DNO_GUI=1 ..
   - cmake --build . --config Release # build libfluidsynth and fluidsynth exec
   - cmake --build . --config Release --target check # build and exec unittests
 
diff --git a/.azure-pipelines.yml b/.azure-pipelines.yml
index 49b7e2d7..00b983a2 100644
--- a/.azure-pipelines.yml
+++ b/.azure-pipelines.yml
@@ -15,7 +15,7 @@ jobs:
     - script: |
         mkdir build && cd build
         export PKG_CONFIG_PATH="/usr/local/opt/libffi/lib/pkgconfig"
-        cmake -DCMAKE_INSTALL_PREFIX=$(Build.ArtifactStagingDirectory) -DCMAKE_BUILD_TYPE=Release -DCMAKE_VERBOSE_MAKEFILE=1 ..
+        cmake -DCMAKE_INSTALL_PREFIX=$(Build.ArtifactStagingDirectory) -DCMAKE_BUILD_TYPE=Release -DCMAKE_VERBOSE_MAKEFILE=1 -DNO_GUI=1 ..
         make
       displayName: 'Compile fluidsynth'
 
@@ -70,7 +70,7 @@ jobs:
         SET "PATH=d:\deps\bin;%PATH%"
         pkg-config --list-all
         mkdir build && cd build || exit -1
-        cmake -A $(platform) -T $(toolset) -DCMAKE_INSTALL_PREFIX=$(Build.ArtifactStagingDirectory) -Denable-readline=0 -Denable-floats=1 -DCMAKE_BUILD_TYPE=Release -DCMAKE_VERBOSE_MAKEFILE=1 .. || exit -1
+        cmake -A $(platform) -T $(toolset) -DCMAKE_INSTALL_PREFIX=$(Build.ArtifactStagingDirectory) -Denable-readline=0 -Denable-floats=1 -DCMAKE_BUILD_TYPE=Release -DCMAKE_VERBOSE_MAKEFILE=1 -DNO_GUI=1 .. || exit -1
         cmake --build . --config Release || exit -1
       displayName: 'Compile fluidsynth'
     - script: |
@@ -142,7 +142,7 @@ jobs:
         @ECHO ON
         SET "PATH=d:\deps\bin;%PATH%"
         mkdir build && cd build || exit -1
-        cmake -A x64 -DCMAKE_BUILD_TYPE=$(CMAKE_CONFIG) -DCMAKE_VERBOSE_MAKEFILE=1 $(CMAKE_FLAGS) .. || exit -1
+        cmake -A x64 -DCMAKE_BUILD_TYPE=$(CMAKE_CONFIG) -DCMAKE_VERBOSE_MAKEFILE=1 $(CMAKE_FLAGS) -DNO_GUI=1 .. || exit -1
         cmake --build . --config $(CMAKE_CONFIG) || exit -1
       displayName: 'Compile fluidsynth'
     - script: |
@@ -204,7 +204,7 @@ jobs:
         set PATH=%PATH:C:\Program Files\Git\usr\bin;=%
         pkg-config --list-all
         mkdir build && cd build || exit -1
-        cmake -G "MinGW Makefiles" -DCMAKE_INSTALL_PREFIX=$(Build.ArtifactStagingDirectory) $(CMAKE_FLAGS) -Denable-readline=0 -DCMAKE_BUILD_TYPE=Release -DCMAKE_VERBOSE_MAKEFILE=1 .. || exit -1
+        cmake -G "MinGW Makefiles" -DCMAKE_INSTALL_PREFIX=$(Build.ArtifactStagingDirectory) $(CMAKE_FLAGS) -Denable-readline=0 -DCMAKE_BUILD_TYPE=Release -DCMAKE_VERBOSE_MAKEFILE=1 -DNO_GUI=1 .. || exit -1
         mingw32-make.exe all || exit -1
       displayName: 'Compile fluidsynth'
     - script: |
diff --git a/.cirrus.yml b/.cirrus.yml
index 43dc0911..3fbb355c 100644
--- a/.cirrus.yml
+++ b/.cirrus.yml
@@ -4,7 +4,7 @@ freebsd_instance:
 task:
   install_script: pwd && ls -la && pkg install -y cmake glib alsa-lib ladspa portaudio pulseaudio pkgconf sdl2
   
-  compile_script: pwd && ls -la && mkdir $HOME/fluidsynth_install/ && mkdir build && cd build && cmake -DCMAKE_INSTALL_PREFIX=$HOME/fluidsynth_install -Denable-portaudio=1 -Denable-ladspa=1 -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_VERBOSE_MAKEFILE=0 .. && make -j4 && make check && make install 
+  compile_script: pwd && ls -la && mkdir $HOME/fluidsynth_install/ && mkdir build && cd build && cmake -DCMAKE_INSTALL_PREFIX=$HOME/fluidsynth_install -Denable-portaudio=1 -Denable-ladspa=1 -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_VERBOSE_MAKEFILE=0  -DNO_GUI=1 .. && make -j4 && make check && make install 
 
   
   
diff --git a/.travis.yml b/.travis.yml
index b9cf86d0..2cbd5e1c 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -59,7 +59,7 @@ before_script:
     - mkdir build && cd build
     
 script:
-    - cmake -DCMAKE_INSTALL_PREFIX=$HOME/fluidsynth_install ${CMAKE_FLAGS} -Denable-portaudio=1 -Denable-ladspa=1 -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_VERBOSE_MAKEFILE=1 ..
+    - cmake -DCMAKE_INSTALL_PREFIX=$HOME/fluidsynth_install ${CMAKE_FLAGS} -Denable-portaudio=1 -Denable-ladspa=1 -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_VERBOSE_MAKEFILE=1 -DNO_GUI=1 ..
     - make -j4
     - make check
     - if [ $TRAVIS_OS_NAME = linux ]; then make install; fi # install only on linux, as CMAKE_INSTALL_PREFIX is ignored for frameworks on macosx and I cant tell whether that's correct or a bug.
diff --git a/src/config.cmake b/src/config.cmake
index 50b5bf12..1f8c8ec7 100644
--- a/src/config.cmake
+++ b/src/config.cmake
@@ -154,6 +154,9 @@
 /* Define to enable network support */
 #cmakedefine NETWORK_SUPPORT @NETWORK_SUPPORT@
 
+/* Defined when fluidsynth is build in an automated enviornment, where no MSVC++ Runtime Debug Assertion dialogs should pop up */
+#cmakedefine NO_GUI @NO_GUI@
+
 /* libinstpatch for DLS and GIG */
 #cmakedefine LIBINSTPATCH_SUPPORT @LIBINSTPATCH_SUPPORT@
 
diff --git a/test/test.h b/test/test.h
index 2df1ebe6..5661d14b 100644
--- a/test/test.h
+++ b/test/test.h
@@ -1,10 +1,29 @@
 
 #pragma once
 
+#include "config.h"
 #include <stdio.h>
 #include <stdlib.h>
 
-#define TEST_ASSERT(COND) do { if (!(COND)) { fprintf(stderr, __FILE__ ":%d assertion (%s) failed\n", __LINE__, #COND); abort(); } } while (0)
+/*
+ * We call abort() because on Linux this sends a signal to the process and causes the debugger to break.
+ *
+ * MSVC++ runtime opens a dialog when abort() is called, saying that abort() has been called and you can
+ * click "Retry" to make the debugger break.
+ * When executed by CI build however, the dialog causes the unit tests to be stuck forever.
+ * Thus suppress the dialog on windows.
+ * MinGW however requires explicit linking against MSVCRT >= 8.0 for _set_abort_behavior().
+ * It's not worth the hassle to implement this with cmake...
+ */
+#if defined(NO_GUI) && defined(MINGW32)
+#define TEST_ABORT exit(EXIT_FAILURE);
+#elif defined(NO_GUI) && defined(WIN32)
+#define TEST_ABORT _set_abort_behavior(0, _WRITE_ABORT_MSG); abort()
+#else
+#define TEST_ABORT abort()
+#endif
+
+#define TEST_ASSERT(COND) do { if (!(COND)) { fprintf(stderr, __FILE__ ":%d assertion (%s) failed\n", __LINE__, #COND); TEST_ABORT; } } while (0)
 
 /* macro to test whether a fluidsynth function succeeded or not */
 #define TEST_SUCCESS(FLUID_FUNCT) TEST_ASSERT((FLUID_FUNCT) != FLUID_FAILED)