diff --git a/.github/workflows/c-tests.yml b/.github/workflows/c-tests.yml
index 7353e59ba..2e3c373d3 100644
--- a/.github/workflows/c-tests.yml
+++ b/.github/workflows/c-tests.yml
@@ -53,7 +53,7 @@ jobs:
       # Doesn't work on Windows.
       - name: Clang Sanitizers
         if: matrix.os != 'windows-latest'
-        run: make sanitize
+        run: CC=clang make sanitize
 
       # Run static analyzer.
       # Doesn't work on Windows.
diff --git a/src/Makefile b/src/Makefile
index 96745cb58..946c8fd55 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -20,7 +20,7 @@ ifeq ($(PLATFORM),Darwin)
 endif
 
 # The base compiler flags. More can be added on command line.
-CFLAGS += -I. -I../inc -O2 -Werror -Wno-gnu-folding-constant
+CFLAGS += -I. -I../inc -O2
 # Enable a bunch of optional warnings.
 CFLAGS += \
 	-pedantic \
@@ -43,6 +43,7 @@ CFLAGS += \
 	-Winit-self \
 	-Winline \
 	-Winvalid-pch \
+	-Wmissing-braces \
 	-Wmissing-declarations \
 	-Wmissing-field-initializers \
 	-Wmissing-format-attribute \
@@ -75,13 +76,15 @@ CFLAGS += \
 
 # Cross-platform compilation settings.
 ifeq ($(PLATFORM),Windows)
-	CC = gcc
+	CC ?= gcc
 	CFLAGS += -D_CRT_SECURE_NO_WARNINGS
-	CFLAGS += -Wno-missing-braces -Wno-format
+	CFLAGS += -Wno-format
 else
-	CC = clang
+	CC ?= clang
 	CFLAGS += -fPIC
-	CFLAGS += -Wmissing-braces -Wformat=2
+ifeq ($(CC),clang)
+	CFLAGS += -Werror -Wno-gnu-folding-constant -Wformat=2
+endif
 endif
 
 # Settings for blst.
@@ -219,7 +222,10 @@ sanitize_%: blst $(SOURCE_FILES) $(HEADER_FILES)
 	    ./$@; rm $@
 
 .PHONY: sanitize
-ifeq ($(PLATFORM),Darwin)
+ifneq ($(CC),clang)
+sanitize:
+	$(error sanitize requires CC=clang)
+else ifeq ($(PLATFORM),Darwin)
 sanitize: \
 	sanitize_address \
 	sanitize_undefined
diff --git a/src/common/ec.h b/src/common/ec.h
index c2cc0f0cb..0db819814 100644
--- a/src/common/ec.h
+++ b/src/common/ec.h
@@ -32,7 +32,7 @@ typedef blst_p2 g2_t; /**< Internal G2 group element type. */
 
 /** Deserialized form of the G1 identity/infinity point. */
 static const g1_t G1_IDENTITY = {
-    {0L, 0L, 0L, 0L, 0L, 0L}, {0L, 0L, 0L, 0L, 0L, 0L}, {0L, 0L, 0L, 0L, 0L, 0L}
+    {{0L, 0L, 0L, 0L, 0L, 0L}}, {{0L, 0L, 0L, 0L, 0L, 0L}}, {{0L, 0L, 0L, 0L, 0L, 0L}}
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
diff --git a/src/common/fr.h b/src/common/fr.h
index 0e97242bb..519051e5e 100644
--- a/src/common/fr.h
+++ b/src/common/fr.h
@@ -41,16 +41,16 @@ typedef blst_fr fr_t; /**< Internal Fr field element type. */
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
 /** The zero field element. */
-static const fr_t FR_ZERO = {0L, 0L, 0L, 0L};
+static const fr_t FR_ZERO = {{0L, 0L, 0L, 0L}};
 
 /** This is 1 in blst's `blst_fr` limb representation. Crazy but true. */
 static const fr_t FR_ONE = {
-    0x00000001fffffffeL, 0x5884b7fa00034802L, 0x998c4fefecbc4ff5L, 0x1824b159acc5056fL
+    {0x00000001fffffffeL, 0x5884b7fa00034802L, 0x998c4fefecbc4ff5L, 0x1824b159acc5056fL}
 };
 
 /** This used to represent a missing element. It's an invalid value. */
 static const fr_t FR_NULL = {
-    0xffffffffffffffffL, 0xffffffffffffffffL, 0xffffffffffffffffL, 0xffffffffffffffffL
+    {0xffffffffffffffffL, 0xffffffffffffffffL, 0xffffffffffffffffL, 0xffffffffffffffffL}
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
diff --git a/src/eip7594/fft.c b/src/eip7594/fft.c
index 91ddd83d8..a629652f1 100644
--- a/src/eip7594/fft.c
+++ b/src/eip7594/fft.c
@@ -35,7 +35,7 @@
  *       printf("%#018llxL,\n", a.l[i]);
  */
 static const fr_t RECOVERY_SHIFT_FACTOR = {
-    0x0000000efffffff1L, 0x17e363d300189c0fL, 0xff9c57876f8457b0L, 0x351332208fc5a8c4L
+    {0x0000000efffffff1L, 0x17e363d300189c0fL, 0xff9c57876f8457b0L, 0x351332208fc5a8c4L}
 };
 
 /**
@@ -48,7 +48,7 @@ static const fr_t RECOVERY_SHIFT_FACTOR = {
  *       printf("%#018llxL,\n", a.l[i]);
  */
 static const fr_t INV_RECOVERY_SHIFT_FACTOR = {
-    0xdb6db6dadb6db6dcL, 0xe6b5824adb6cc6daL, 0xf8b356e005810db9L, 0x66d0f1e660ec4796L
+    {0xdb6db6dadb6db6dcL, 0xe6b5824adb6cc6daL, 0xf8b356e005810db9L, 0x66d0f1e660ec4796L}
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
diff --git a/src/setup/setup.c b/src/setup/setup.c
index 5d8d4972d..1686afaef 100644
--- a/src/setup/setup.c
+++ b/src/setup/setup.c
@@ -79,7 +79,7 @@
  * factor changes, this constant is no longer correct.
  */
 static const fr_t ROOT_OF_UNITY = {
-    0xa33d279ff0ccffc9L, 0x41fac79f59e91972L, 0x065d227fead1139bL, 0x71db41abda03e055L
+    {0xa33d279ff0ccffc9L, 0x41fac79f59e91972L, 0x065d227fead1139bL, 0x71db41abda03e055L}
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////