diff --git a/src/exact_value.cpp b/src/exact_value.cpp
index 2f82a52cf..5c436fee6 100644
--- a/src/exact_value.cpp
+++ b/src/exact_value.cpp
@@ -1019,6 +1019,10 @@ gb_internal bool compare_exact_values(TokenKind op, ExactValue x, ExactValue y)
 		f64 b = x.value_complex->imag;
 		f64 c = y.value_complex->real;
 		f64 d = y.value_complex->imag;
+		if (isnan(a) || isnan(b) || isnan(c) || isnan(d)) {
+			return op == Token_NotEq;
+		}
+
 		switch (op) {
 		case Token_CmpEq: return cmp_f64(a, c) == 0 && cmp_f64(b, d) == 0;
 		case Token_NotEq: return cmp_f64(a, c) != 0 || cmp_f64(b, d) != 0;
@@ -1026,6 +1030,29 @@ gb_internal bool compare_exact_values(TokenKind op, ExactValue x, ExactValue y)
 		break;
 	}
 
+	case ExactValue_Quaternion: {
+		Quaternion256 a = *x.value_quaternion;
+		Quaternion256 b = *y.value_quaternion;
+		if (isnan(a.real) || isnan(a.imag) || isnan(a.jmag) || isnan(a.kmag) ||
+		    isnan(b.real) || isnan(b.imag) || isnan(b.jmag) || isnan(b.kmag)) {
+			return op == Token_NotEq;
+		}
+
+		switch (op) {
+		case Token_CmpEq:
+			return cmp_f64(a.real, b.real) == 0 &&
+			       cmp_f64(a.imag, b.imag) == 0 &&
+			       cmp_f64(a.jmag, b.jmag) == 0 &&
+			       cmp_f64(a.kmag, b.kmag) == 0;
+		case Token_NotEq:
+			return cmp_f64(a.real, b.real) != 0 ||
+			       cmp_f64(a.imag, b.imag) != 0 ||
+			       cmp_f64(a.jmag, b.jmag) != 0 ||
+			       cmp_f64(a.kmag, b.kmag) != 0;
+		}
+		break;
+	}
+
 	case ExactValue_String: {
 		String a = x.value_string;
 		String b = y.value_string;
diff --git a/tests/internal/test_quaternion_comparison.odin b/tests/internal/test_quaternion_comparison.odin
new file mode 100644
index 000000000..93de83b8e
--- /dev/null
+++ b/tests/internal/test_quaternion_comparison.odin
@@ -0,0 +1,130 @@
+package test_internal
+
+import "core:testing"
+
+// Each constant case is paired with the same comparison on variables: the folded answer
+// has to be the answer the backend produces.
+
+@(test)
+compare_constant_quaternions :: proc(t: ^testing.T) {
+	I :: quaternion128(0+1i+0j+0k)
+	J :: quaternion128(0+0i+1j+0k)
+	K :: quaternion128(0+0i+0j+1k)
+	R :: quaternion128(1+0i+0j+0k)
+
+	testing.expect_value(t, R == 1,  true)
+	testing.expect_value(t, 1 == R,  true)
+	testing.expect_value(t, R != 1,  false)
+	testing.expect_value(t, I == J,  false)
+	testing.expect_value(t, J == K,  false)
+	testing.expect_value(t, K == R,  false)
+	testing.expect_value(t, I != J,  true)
+	testing.expect_value(t, I == I,  true)
+
+	// every lane must take part, not just the real one
+	A :: quaternion128(2+3i+4j+5k)
+	testing.expect_value(t, A == quaternion128(2+3i+4j+5k), true)
+	testing.expect_value(t, A == quaternion128(9+3i+4j+5k), false)
+	testing.expect_value(t, A == quaternion128(2+9i+4j+5k), false)
+	testing.expect_value(t, A == quaternion128(2+3i+9j+5k), false)
+	testing.expect_value(t, A == quaternion128(2+3i+4j+9k), false)
+
+	// promotion of the other operand, from integer, float and complex
+	testing.expect_value(t, R == 1.0, true)
+	testing.expect_value(t, quaternion128(2+3i+0j+0k) == 2+3i, true)
+	testing.expect_value(t, quaternion128(2+3i+0j+0k) == 2+4i, false)
+
+	testing.expect_value(t, quaternion64(0) == 0,  true)
+	testing.expect_value(t, quaternion256(0) == 0, true)
+	testing.expect_value(t, quaternion128(0) == quaternion128(-0.0), true)
+}
+
+@(test)
+compare_variable_quaternions :: proc(t: ^testing.T) {
+	I := quaternion128(0+1i+0j+0k)
+	J := quaternion128(0+0i+1j+0k)
+	K := quaternion128(0+0i+0j+1k)
+	R := quaternion128(1+0i+0j+0k)
+
+	testing.expect_value(t, R == 1,  true)
+	testing.expect_value(t, 1 == R,  true)
+	testing.expect_value(t, R != 1,  false)
+	testing.expect_value(t, I == J,  false)
+	testing.expect_value(t, J == K,  false)
+	testing.expect_value(t, K == R,  false)
+	testing.expect_value(t, I != J,  true)
+	testing.expect_value(t, I == I,  true)
+
+	A := quaternion128(2+3i+4j+5k)
+	testing.expect_value(t, A == quaternion128(2+3i+4j+5k), true)
+	testing.expect_value(t, A == quaternion128(9+3i+4j+5k), false)
+	testing.expect_value(t, A == quaternion128(2+9i+4j+5k), false)
+	testing.expect_value(t, A == quaternion128(2+3i+9j+5k), false)
+	testing.expect_value(t, A == quaternion128(2+3i+4j+9k), false)
+
+	testing.expect_value(t, R == 1.0, true)
+	testing.expect_value(t, quaternion128(2+3i+0j+0k) == 2+3i, true)
+	testing.expect_value(t, quaternion128(2+3i+0j+0k) == 2+4i, false)
+
+	q64  := quaternion64(0)
+	q256 := quaternion256(0)
+	testing.expect_value(t, q64  == 0, true)
+	testing.expect_value(t, q256 == 0, true)
+	testing.expect_value(t, quaternion128(0) == quaternion128(-0.0), true)
+}
+
+@(test)
+compare_constant_quaternion_nans :: proc(t: ^testing.T) {
+	NaN :: f64(0h7ff8_0000_0000_0000)
+	Q   :: quaternion(w=NaN, x=0, y=0, z=0)
+	L   :: quaternion(w=0, x=0, y=0, z=NaN)
+
+	testing.expect_value(t, Q == Q, false)
+	testing.expect_value(t, Q != Q, true)
+	testing.expect_value(t, L == L, false)
+	testing.expect_value(t, L != L, true)
+	testing.expect_value(t, Q == 0, false)
+	testing.expect_value(t, Q != 0, true)
+}
+
+@(test)
+compare_variable_quaternion_nans :: proc(t: ^testing.T) {
+	NaN := f64(0h7ff8_0000_0000_0000)
+	Q   := quaternion(w=NaN, x=0, y=0, z=0)
+	L   := quaternion(w=0, x=0, y=0, z=NaN)
+
+	testing.expect_value(t, Q == Q, false)
+	testing.expect_value(t, Q != Q, true)
+	testing.expect_value(t, L == L, false)
+	testing.expect_value(t, L != L, true)
+	testing.expect_value(t, Q == 0, false)
+	testing.expect_value(t, Q != 0, true)
+}
+
+@(test)
+compare_constant_complex_nans :: proc(t: ^testing.T) {
+	NaN :: f64(0h7ff8_0000_0000_0000)
+	C   :: complex(NaN, 0)
+	D   :: complex(0, NaN)
+
+	testing.expect_value(t, C == C, false)
+	testing.expect_value(t, C != C, true)
+	testing.expect_value(t, D == D, false)
+	testing.expect_value(t, D != D, true)
+	testing.expect_value(t, C == 0, false)
+	testing.expect_value(t, C != 0, true)
+}
+
+@(test)
+compare_variable_complex_nans :: proc(t: ^testing.T) {
+	NaN := f64(0h7ff8_0000_0000_0000)
+	C   := complex(NaN, 0)
+	D   := complex(0, NaN)
+
+	testing.expect_value(t, C == C, false)
+	testing.expect_value(t, C != C, true)
+	testing.expect_value(t, D == D, false)
+	testing.expect_value(t, D != D, true)
+	testing.expect_value(t, C == 0, false)
+	testing.expect_value(t, C != 0, true)
+}