diff --git a/Makefile b/Makefile
index f0d2d2d87..f772ed9db 100644
--- a/Makefile
+++ b/Makefile
@@ -85,6 +85,13 @@ all: | $(TOOLS) libnfuzz.so libnfuzz.a
 # must be included after the default target
 -include $(BUILD_SYSTEM_DIR)/makefiles/targets.mk
 
+ifeq ($(OS), Windows_NT)
+  ifeq ($(ARCH), x86)
+    # 32-bit Windows is not supported by libbacktrace/libunwind
+    USE_LIBBACKTRACE := 0
+  endif
+endif
+
 # "--define:release" implies "--stacktrace:off" and it cannot be added to config.nims
 ifeq ($(USE_LIBBACKTRACE), 0)
 NIM_PARAMS := $(NIM_PARAMS) -d:debug -d:disable_libbacktrace
diff --git a/azure-pipelines.yml b/azure-pipelines.yml
index f6a62c346..b809912c2 100644
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -65,10 +65,14 @@ jobs:
           mingw32-make -j2 ARCH_OVERRIDE=${PLATFORM} CI_CACHE=NimBinaries update
           mingw32-make -j2 ARCH_OVERRIDE=${PLATFORM} fetch-dlls
           mingw32-make -j2 ARCH_OVERRIDE=${PLATFORM} LOG_LEVEL=TRACE
-          mingw32-make -j2 ARCH_OVERRIDE=${PLATFORM} LOG_LEVEL=TRACE NIMFLAGS="-d:testnet_servers_image"
+          if [[ $PLATFORM == "x64" ]]; then
+            # everything builds more slowly on 32-bit, since there's no libbacktrace support
+            mingw32-make -j2 ARCH_OVERRIDE=${PLATFORM} LOG_LEVEL=TRACE NIMFLAGS="-d:testnet_servers_image"
+          fi
           file build/beacon_node
           # fail fast
           export NIMTEST_ABORT_ON_ERROR=1
           scripts/setup_official_tests.sh jsonTestsCache
           mingw32-make -j2 ARCH_OVERRIDE=${PLATFORM} DISABLE_TEST_FIXTURES_SCRIPT=1 test
         displayName: 'build and test'
+
diff --git a/beacon_chain.nimble b/beacon_chain.nimble
index 03f778d36..c88e5d40a 100644
--- a/beacon_chain.nimble
+++ b/beacon_chain.nimble
@@ -37,7 +37,7 @@ requires "nim >= 0.19.0",
   "yaml"
 
 ### Helper functions
-proc buildBinary(name: string, srcDir = "./", params = "", cmdParams = "", lang = "c") =
+proc buildAndRunBinary(name: string, srcDir = "./", params = "", cmdParams = "", lang = "c") =
   if not dirExists "build":
     mkDir "build"
   # allow something like "nim test --verbosity:0 --hints:off beacon_chain.nims"
@@ -47,7 +47,7 @@ proc buildBinary(name: string, srcDir = "./", params = "", cmdParams = "", lang
   exec "nim " & lang & " --out:./build/" & name & " -r " & extra_params & " " & srcDir & name & ".nim" & " " & cmdParams
 
 task moduleTests, "Run all module tests":
-  buildBinary "beacon_node", "beacon_chain/",
+  buildAndRunBinary "beacon_node", "beacon_chain/",
               "-d:chronicles_log_level=TRACE " &
               "-d:const_preset=minimal -d:ETH2_SPEC=\"v0.12.1\" -d:BLS_ETH2_SPEC=\"v0.12.x\" " &
               "-d:testutils_test_build"
@@ -58,35 +58,46 @@ task test, "Run all tests":
   # pieces of code get tested regularly. Increased test output verbosity is the
   # price we pay for that.
 
+  # Mainnet tests are not enabled on 32-bit Windows, to avoid a 1h20m timeout on
+  # Azure Pipelines (there's no libbacktrace/libunwind support there, and the
+  # performance hit is big).
+
   # Minimal config
-  buildBinary "proto_array", "beacon_chain/fork_choice/", "-d:const_preset=minimal -d:ETH2_SPEC=\"v0.12.1\" -d:BLS_ETH2_SPEC=\"v0.12.x\""
-  buildBinary "fork_choice", "beacon_chain/fork_choice/", "-d:const_preset=minimal -d:ETH2_SPEC=\"v0.12.1\" -d:BLS_ETH2_SPEC=\"v0.12.x\""
-  buildBinary "all_tests", "tests/", "-d:chronicles_log_level=TRACE -d:const_preset=minimal -d:ETH2_SPEC=\"v0.12.1\" -d:BLS_ETH2_SPEC=\"v0.12.x\""
-  # Mainnet config
-  buildBinary "proto_array", "beacon_chain/fork_choice/", "-d:const_preset=mainnet -d:ETH2_SPEC=\"v0.12.1\" -d:BLS_ETH2_SPEC=\"v0.12.x\""
-  buildBinary "fork_choice", "beacon_chain/fork_choice/", "-d:const_preset=mainnet -d:ETH2_SPEC=\"v0.12.1\" -d:BLS_ETH2_SPEC=\"v0.12.x\""
-  buildBinary "all_tests", "tests/", "-d:const_preset=mainnet -d:ETH2_SPEC=\"v0.12.1\" -d:BLS_ETH2_SPEC=\"v0.12.x\""
+  buildAndRunBinary "proto_array", "beacon_chain/fork_choice/", "-d:const_preset=minimal -d:ETH2_SPEC=\"v0.12.1\" -d:BLS_ETH2_SPEC=\"v0.12.x\""
+  buildAndRunBinary "fork_choice", "beacon_chain/fork_choice/", "-d:const_preset=minimal -d:ETH2_SPEC=\"v0.12.1\" -d:BLS_ETH2_SPEC=\"v0.12.x\""
+  buildAndRunBinary "all_tests", "tests/", "-d:chronicles_log_level=TRACE -d:const_preset=minimal -d:ETH2_SPEC=\"v0.12.1\" -d:BLS_ETH2_SPEC=\"v0.12.x\""
+  when not (defined(windows) and defined(i386)):
+    # Mainnet config
+    buildAndRunBinary "proto_array", "beacon_chain/fork_choice/", "-d:const_preset=mainnet -d:ETH2_SPEC=\"v0.12.1\" -d:BLS_ETH2_SPEC=\"v0.12.x\""
+    buildAndRunBinary "fork_choice", "beacon_chain/fork_choice/", "-d:const_preset=mainnet -d:ETH2_SPEC=\"v0.12.1\" -d:BLS_ETH2_SPEC=\"v0.12.x\""
+    buildAndRunBinary "all_tests", "tests/", "-d:const_preset=mainnet -d:ETH2_SPEC=\"v0.12.1\" -d:BLS_ETH2_SPEC=\"v0.12.x\""
 
   # Generic SSZ test, doesn't use consensus objects minimal/mainnet presets
-  buildBinary "test_fixture_ssz_generic_types", "tests/official/", "-d:chronicles_log_level=TRACE"
+  buildAndRunBinary "test_fixture_ssz_generic_types", "tests/official/", "-d:chronicles_log_level=TRACE"
 
   # Consensus object SSZ tests
   # 0.11.3
-  buildBinary "test_fixture_ssz_consensus_objects", "tests/official/", "-d:chronicles_log_level=TRACE -d:const_preset=minimal -d:ETH2_SPEC=\"v0.11.3\""
-  buildBinary "test_fixture_ssz_consensus_objects", "tests/official/", "-d:const_preset=mainnet -d:ETH2_SPEC=\"v0.11.3\""
+  buildAndRunBinary "test_fixture_ssz_consensus_objects", "tests/official/", "-d:chronicles_log_level=TRACE -d:const_preset=minimal -d:ETH2_SPEC=\"v0.11.3\""
+  when not (defined(windows) and defined(i386)):
+    buildAndRunBinary "test_fixture_ssz_consensus_objects", "tests/official/", "-d:const_preset=mainnet -d:ETH2_SPEC=\"v0.11.3\""
 
   # 0.12.1
-  buildBinary "test_fixture_ssz_consensus_objects", "tests/official/", "-d:chronicles_log_level=TRACE -d:const_preset=minimal -d:ETH2_SPEC=\"v0.12.1\" -d:BLS_ETH2_SPEC=\"v0.12.x\""
-  buildBinary "test_fixture_ssz_consensus_objects", "tests/official/", "-d:const_preset=mainnet -d:ETH2_SPEC=\"v0.12.1\" -d:BLS_ETH2_SPEC=\"v0.12.x\""
+  buildAndRunBinary "test_fixture_ssz_consensus_objects", "tests/official/", "-d:chronicles_log_level=TRACE -d:const_preset=minimal -d:ETH2_SPEC=\"v0.12.1\" -d:BLS_ETH2_SPEC=\"v0.12.x\""
+  when not (defined(windows) and defined(i386)):
+    buildAndRunBinary "test_fixture_ssz_consensus_objects", "tests/official/", "-d:const_preset=mainnet -d:ETH2_SPEC=\"v0.12.1\" -d:BLS_ETH2_SPEC=\"v0.12.x\""
 
   # 0.11.3
-  buildBinary "all_fixtures_require_ssz", "tests/official/", "-d:chronicles_log_level=TRACE -d:const_preset=minimal -d:ETH2_SPEC=\"v0.11.3\""
-  buildBinary "all_fixtures_require_ssz", "tests/official/", "-d:const_preset=mainnet -d:ETH2_SPEC=\"v0.11.3\""
+  buildAndRunBinary "all_fixtures_require_ssz", "tests/official/", "-d:chronicles_log_level=TRACE -d:const_preset=minimal -d:ETH2_SPEC=\"v0.11.3\""
+  when not (defined(windows) and defined(i386)):
+    buildAndRunBinary "all_fixtures_require_ssz", "tests/official/", "-d:const_preset=mainnet -d:ETH2_SPEC=\"v0.11.3\""
 
   # 0.12.1
-  buildBinary "all_fixtures_require_ssz", "tests/official/", "-d:chronicles_log_level=TRACE -d:const_preset=minimal -d:ETH2_SPEC=\"v0.12.1\" -d:BLS_ETH2_SPEC=\"v0.12.x\""
-  buildBinary "all_fixtures_require_ssz", "tests/official/", "-d:const_preset=mainnet -d:ETH2_SPEC=\"v0.12.1\" -d:BLS_ETH2_SPEC=\"v0.12.x\""
+  buildAndRunBinary "all_fixtures_require_ssz", "tests/official/", "-d:chronicles_log_level=TRACE -d:const_preset=minimal -d:ETH2_SPEC=\"v0.12.1\" -d:BLS_ETH2_SPEC=\"v0.12.x\""
+  when not (defined(windows) and defined(i386)):
+    buildAndRunBinary "all_fixtures_require_ssz", "tests/official/", "-d:const_preset=mainnet -d:ETH2_SPEC=\"v0.12.1\" -d:BLS_ETH2_SPEC=\"v0.12.x\""
 
   # State sim; getting into 4th epoch useful to trigger consensus checks
-  buildBinary "state_sim", "research/", "-d:const_preset=minimal -d:ETH2_SPEC=\"v0.12.1\" -d:BLS_ETH2_SPEC=\"v0.12.x\"", "--validators=2000 --slots=32"
-  buildBinary "state_sim", "research/", "-d:const_preset=mainnet -d:ETH2_SPEC=\"v0.12.1\" -d:BLS_ETH2_SPEC=\"v0.12.x\"", "--validators=2000 --slots=128"
+  buildAndRunBinary "state_sim", "research/", "-d:const_preset=minimal -d:ETH2_SPEC=\"v0.12.1\" -d:BLS_ETH2_SPEC=\"v0.12.x\"", "--validators=2000 --slots=32"
+  when not (defined(windows) and defined(i386)):
+    buildAndRunBinary "state_sim", "research/", "-d:const_preset=mainnet -d:ETH2_SPEC=\"v0.12.1\" -d:BLS_ETH2_SPEC=\"v0.12.x\"", "--validators=2000 --slots=128"
+